I dunno, Anime tie-ins are usually pretty standard, but Inuyasha's
huge, and back then it pulled in a lot of famous singers who didn't normally do anime OP/EDs, so I think we can say Inuyasha's an exception of sorts.
That being said, I think it'd be pretty cool if they went back and got some of the old singers (Namie, Ayu, and as they're already doing, DAI, etc.) to sing new themes for them, or just use already made songs by them. I didn't exactly discover Ayu through Inuyasha, but it was still one of the earliest instances I had of being exposed to her music, and it gives Dearest and no more words some sentimental value to them that other songs obviously won't have.
Also, as can be seen from this thread alone, LOTS of people's first song was Dearest because of Inuyasha, so I think it's safe to say that having an anime tie-in with something like Inuyasha could definitely help her fanbase, even if it is overseas. I don't think I'd object to more Ayu fans, haha...
Plus again, the whole sentimental value thing; I think it'd be great for newer fans to have a song they can associate with something they really love (like I did with Dearest/no more words during my Inuyasha phase), it makes it a bit more special than just a random single being released.
/0.02$
