I think JPEG XL can stand on it's own merits, even with Google's apparent sabotage. The format is good, vastly better than JPEG/PNG/GIF and similar to WebP (beats it in some areas and I think overall better in feature set).
And honestly, how long has WebP been out, even with Google backing, and it's barely supported anywhere. So I don't think they are a good judge of standards.
JPEG is just ancient technology, it was made when people were using 14.4 K modems. We shouldn't still be using it. PNG is a solid format, but GIF could not be worse.
And every other new format has been destroyed by either patent encumbrance or these stupid corporate format wars (which always end up with everyone losing).
I think JPEG XL still has a shot, and if the open source community adopts it and it gets better support, Google will eventually add it back in.
And, to be honest, it's not finished. So it is technically experimental, last time I tried the SDK it didn't even compile. So it could still happen.