If you see a notice from WGT at some point saying in effect we are no longer selling items, then I would get worried.
I played the WGT Baseball game for almost 2 years. Loved it. Then, one day, I noticed the 2-3 month updates were no longer coming, so I wrote CS. They told me "we're always working on new features and updates, but we can't disclose the date of next update".
A few months went by, same message. About a week later, WGT announced it was shutting down the baseball game on Dec 31st 2018 (this was in October, I think). They still had the items for sale all the way until Dec 1st, then the store disappeared, then the game went away as scheduled. :-(
I remember a question from one of the mods (Champ, maybe) asking if we'd still play if WGT was downloaded instead of browser. The only way they could switch would be to switch platforms (HTML5 or Steam....love steam and VAC). Maybe they're working on switching over.
WGT outliving flash doesn't mean anything other than the mobile version will be here forever.
I use a 2016/2017 browser (Slimjet 10.0.7.0) that was the last version of chromium browsers to allow NPAPI. I have PPAPI disabled and always keep flash updated whenever new versions or patches come out.
Game has always been smooth as silk (knock on wood).