Further to Tmuir's (almost) spot on reply

Yes, you could stay on the current wallet and continue to mine coins with that wallet, however you would only be able to exchange those coins with other people on that version. Any OLD coins mined after the fork would show in an updated wallet as greyed out and unable to send/mint or do anything.

That's the side of open source that's groovy, if you want to roll out a change, you need to get a sufficient number of people to to use it. So if this dev turns out to be a crook and puts some code in the new wallet where 30% of mined coins are set to his personal wallet, we can all just swtich back to the current version and his mischievous endeavors would be for nothing if he can't convince ~80% or so of us that it's a good thing

Open Office is a good example. People weren't happy with the direction that was going in, so a group formed up to fork the code and it became Libre Office, which is now the go-to for many pepole, leaving the OoO guy's holding their hats.