Hmm, while a very interesting idea I find it rather doubtful.
I find the idea of the Grimm going away (In the sense of being so changed as to be unrecognizable) is unlikely and given the looming threat of the gods genocide, and Salem being as much a character as a villain I can't really envision this feeling particularly satisfying. Especially if they can only do it by asking the Blacksmith for help as it feels kind of like they just had an idea, but otherwise only won by getting help on a science experiment, which itself would feel kind of tonally off for the series.
Ultimately, to me it doesn't really feel like much of a resolution, oh it would in universe certainly but from a story telling perspective much less so I'm afraid. Plus they'd still need to get the Relics back from Salem and this would also kind of imply the Grimm are all a hive mind/essence... Something which I don't think is well supported by canon.