They'll just stop distributing versions through the Mac App store and the Mac App store will become even more irrelevant.
If they need to drop Electron to get into the more lucrative 30% of the mobile market, iOS users, they'll do it as fast as they can...
There's no such thing as a "free" app from a for-profit company -- except some neglected side project.
Spotify is only free because they want to hook people and then sell premium subscriptions to those that are up for it, others are monetized by ads, private info (eyeballs), etc.
And one app not being on there isn't going to change that.