The situation won’t be that dire anyway, as unofficial Android ROMs tend to offer quite good performance overall, at least when they’re done right, so users shouldn’t have to worry about any performance losses when using custom ROMs. They will still have to wait for a release to be made in the first place though, and that may take a while.
We will have to wait and see how the situation develops on the official side, and whether Motorola end up supporting the device additionally or not. At this point though, it’s becoming more and more likely that we’ll stop hearing about updates to the G2 in the future.
The device still had a nice run and it managed to establish a good name for itself on the market, possibly setting up Motorola for even more solid releases in the future. They haven’t given any hints about that so far, but Motorola is a pretty secretive company in general, at least when it comes to their smartphone projects.