I'm personally not a fan of Nintendo games having voice actors. To me, Nintendo essentially adopted this due to the fact that the popular series don't have voice actors (by this I mean message voice actors), and I really like that this is the case.
As for Sinnoh remakes, I feel like they should wait until another handheld device is released. Like others said before me, DPPt and HGSS are currently able to be played on any 3DS or 2DS. Regarding the previous remakes, the games couldn't be played on the newly released handhelds, so in these cases, the remakes were justified. That being said, there isn't a doubt in my mind that there will eventually be a remake in the future (Gen VIII?).
So let's not get ahead of ourselves! Let's enjoy ORAS for what it is -- a Hoenn remake!