The IDEs are being maintained. ni / the language / the Standard Rules haven’t changed, but the IDEs have had updates. But none of them are integrated with the Friends repo for extensions, so far as I know, which creates a less than great situation for newcomers. (But I’m not that well-versed in the IDEs, having homebrewed a CLI alternative to the IDE to avoid them…)
I don’t think parser IF is at any great risk. The I7 community is still pretty active; there’s an active retrocomputing community writing I6 games with the PunyInform library; there’s still TADS; there’s a ZIL revival; there are recent platforms like Dialog and Gruescript.
I think an updated I7 Handbook could be incredibly useful. The docs don’t offer a great on-ramp for beginners; Aaron Reed’s Creating Interactive Fiction with I7 was for 6E72; the Handbook fills an important niche. And it’d be especially valuable if it spelled out how to deal with extensions in the modern world, 'cause if it did it would kind of automatically become the best guide available on the subject.
But my guess is that the next release of I7, when it comes, is going to look more like the 6G60->6L02 transition in terms of breaking things than the subsequent version changes. So, personally, I do think it makes sense to ponder whether it’s worth the time to sink a lot of effort into something specific to 6M62. (I’ve done so, myself…)