Yes that is something to consider with the tractor. As I see it, one option is to just use a block heater on the tractor for an hour or so before each time you use it if that makes starting it possible. You can get things like wifi plugs that would allow you to activate the heater remotely. So you could do that and just hope it keeps running for a while to buy yourself some time.
Now from personal experience I will say sometimes having old stuff is fun and saves some money but if its always breaking down, taking you away from other projects that you really need to do, or if just doesn't work half the time then it might not be worthwhile and might be best to sell and buy new or newer.
I will say My John Deere 2032R has been a pretty bullet proof machine, and has done everything I asked of it, and its also easy to service/work on myself so the ongoing cost of ownership is low, actually the biggest cost is the $33/mo it costs to have it insured at replacement value. Now I will say I bought it because as you know I had a lot of work to do on the property I bought and would have been paying a lot of money to rent machines or hire companies with equipment to do all the work I had to do. If I didn't have a bunch of land clearing and construction work the cost would have been vwry hard to justify. Which brings me to my next point and that is the cost of a new tractor is substantial.
So i'd say if you find yourself using the tractor a lot and really need it, then if you can afford it buying a new tractor might make a lot of sense as it will just work, you won't have to worry about it and can do all the other things you need to do. Additionally you will gain a bunch or new features if you want them, such as a removable loader, quick connects, rear hydralics, quick attach 3pt, mid PTO, 3rd function, light options, built-in block heaters, 4wd, much newer style radial tire options etc... Also I can say I have never regretted buying my tractor new.
On the other hand if the tractor is more of a nice to have item that you don't use all that much or don't really need. Then i'd just try to limp the old one along as long as possible.
Finally, if you do buy a new tractor make sure to get one large enough to do the stuff you need to do and give lots of though to what 'options' will be useful and worthwhile when ordering it. And of course be sure it can run an implements you already own.