Greif little in all likely hood will change the fanbase will most likely slowly shrink & the game will continue in its final form. Chances of it getting further game engine updates will be very slim need a major programing fan or 2 to step in. Emulators will run it on future operating sytstems & if they cant there is a reasonably good chance somebody will hot fix the game so it works. People will start dabling more with OOBs n come up with there version, so some nations will die out past 2020 as nobody does a new OOB for it. Shrapnel will still keep this site active for a while they dont just shut the door n say tough & a few people might set up a site of there own. Look at SPWAW & its still going, infact it probably gets better support now than Matrix ever gave it though that wont be the case with this game.
What does all this mean
You will have to get more hands on getting it to run might take a bit of dedication, playing a battle after 2020 will require you to swap OOBs (dead easy) & send a copy to your opponent for PBEMs. Need to swap cause without recoding playing a battle in 2021 means you will have to use a diffrent date to simulate it say 1951 -60 represent 2021-30 You might be more inclined to build your own OOBs for your favorite countries or modify somebodys take on it. Finland certainly wont stop in 2020 its more a case of which one to choose based on past record

If you like to play all your battles in the current year then you had best learn the OOB editor but if you play as most do battles from diffrent time periods you will continue fighting the battles you always have. And you might just decide to download somebodys OOB & take it for a spin if fancy playing something based in the current year. After all 1 or 2 people still play WinSPWW2 & the dates there ended 60 odd years ago.
1 fan with programing skills capable of getting it running & a good search engine to find it is all it will take to keep this game alive on the majority of systems so your in the lap of the gods that your system isnt the one it wont work on & that this guy exists somewhere out there.
If Don n Andy are kind enough to release the CD version to the public domain once they feel the profits have dried up theres a good chance these games will outlive them. People arent going to stop downloading this "old school" game n trying it just because its 2020 something the same type of person will try it & like it as now.