You may be shocked about the capabilities of this machine and a blade. I have a blade and a blower. I often go several years between needing the blower. The HDAP tires have lots of traction even without chains. Not sure what you get for snow and that is going to be a big factor. For instance if you live in an area with lots of lake effect snow or with no trees and you get a lot of drifting, then you are right, you will probably need a blower. While I live in MN, we have a lot of trees so we don't get very much drifting. We have a small dog as well and I plow a poop path for her. We probably have 1.5' of snow total on the ground but I keep the paths open. So really that means I am only plowing 1-8" of snow at a time depending on the storm. I push the snow out into the yard but I also don't have a manicured lawn by any means. If I scalp some in the process, I don't care much. Also by stripping away the snow like that it is harder on the grass as it doesn't have the protection from the cold when it dips way below 0F. If those things are deal killers, then a blower is a better option. My biggest gripe with my blower is we have so many buildings and windows around that it never fails, I have to blow into the wind. Now that is a job that will freeze you to the bone. More so when it is powdery snow. Because of that I will always plow powder. If I do put the blower on, it is likely because we got slammed with 12" of wet heavy snow which doesn't happen that often. Blowers also don't work when there is a little bit of snow. They need at least 2-3" or they don't seem to work well. That seems like the range of most of our snow falls. When it is 12" of heavy stuff, I can still plow it but it takes forever because if you angle the blade to widen the path down the driveway, the weight of the snow just pushes you over so you are lucky to make the path 6" wider with each path. The tractor just doesn't have enough weight. Because everything is shaft driven, it is a matter of two pins to drop the blade. You pin the pivot of the quick hitch to hold it straight, pull up to and pickup the blower, hook up the drive shaft, disconnect the two hydraulic lines for pivoting the blade and replace them with the hydraulic lines to turn the chute. That is about it. No tools and maybe a 5 min change over. Oh you might have to hook up the mid PTO shaft if you didn't install that. I normally leave mine hooked up all winter just in case since you have to crawl under the tractor to hook it up.
In the winter I bring my blower up from one of the storage buildings just in case. It is sitting out in the garage right now in front of the truck. That said if I know we are getting 12"+ of wet heavy snow, I just go out and plow mid storm and I do fine.
One thing to look at on those machines is the PTO pass through for the blower. I mentioned the PTO mid shaft above for the blower. The way it works is there is a mid PTO output on the front side of the rear axle. This is where the mower deck hooks up in summer months. When you take the mower off and go to use the blower, there is a shaft that goes from the output spline on the rear axle (where the mower was hooked up) and it passes under the tractor to a spline that passes through the front axle and out the front of the tractor. I mention this because, and I don't know for sure on this, but I think that pto shaft pass through is only installed when the dealer sets a machine up for a blower. I can't think of any other attachment that uses the front PTO like that other than the blower or broom. If the machine wasn't set up for one of those two it might not have it installed. I seem to remember some people asking about how to install that which makes me think it might not be standard. It is another thing you might need which could add to the cost of a blower. I just don't know for sure since our machine came with the blower, blade and mower.
Here is a video on installing the blower. If you watch the entire thing, much of it is the change over from mowing to snow and is just done in the fall/spring. If going from blower to blade much of this will remain the same. Fast forward to 1:21 to see the mid shaft and the pass through shaft that I was talking about. Then at 3:04 he is hooking up the driveshaft.
Here is a thread where I think someone was installing the front PTO shaft that passes through the front axle. You can see there are a couple pics where there were caps that he pulled. The shaft is installed through there. Once that is installed, you don't have to mess with it anymore.
I think this is the driveshaft pass through. If not there you would need one of these plus all the bearings, seals and related parts. That shaft might not be the exact part for your machine but an example. The dealer would be able to look it up.
Another thing to ask is about that front blade. Like I said a 66" isn't normal for a John Deere front blade. My guess is it is a CTA or some other 3rd party blade. That can be fine. The CTA blades are nice. However you want to make sure the quick hitch that the blade mounts to is the John Deere one. This is the part with the hydraulic cylinders. If you want to get a blower later, if this isn't the JD version of a quick hitch, you might have to add that to your blower purchase. That will tack on another $700 at least to the blower which is already several thousand unless you score a used one. It is entirely possible that to add a blower to either one of them could be in the $3k range depending on how it is set up now with the mid/front shaft and quick hitch.
This is a big part of why I am on the fence about replacing my X585. Part of me is leaning toward a 3025E because I don't need a mid PTO for a mower. I have the Z950R. If I don't have a mid PTO (the 3E machines only have rear) then I can't do a front blower. I hate to have that much cash tied up in an attachment that sees so little use. If I get a bigger machine, which the 3 series is huge compared to what I have, I likely will have less problems plowing than I do now so there is even less use for a blower. If I really found I needed one, I could pick up a used rear mounted blower. While they kind of suck using being you have to back up. It would be used so infrequently that it really doesn't matter.
This is how I use my machines. I have a coworker with a house in the country but he isn't in a wooded area. His house is along the edge of a field and all it takes is a windy day and he is back out there clearing his 1/4 mile driveway as it drifts over. For him he has to use a blower and he doesn't own a blade.