Well they are known for patterns and they hardly ever stray from them in game. So yea it does cut Sinnoh/Hoenn Pokemon out of the picture, Pre-E4 anyway.Why not have Sinnoh evos? Just being a Remake doesn't cut the Sinnoh evos right out...in fact the only thing to suggest that is Frlg which isn't much of a pattern...it's one game. Nintendo would try and make the game as fun and money making as possible and in my eyes having some extra little things like that help.
As much as money means to any company there is tradition, and I for one would not like to see HGSS pre-E4 play through soiled with pokemon not availibe in the originals, that's not to say I wouldn't support things like Houndour avalible a bit earlier than Lavendar Town.
After E4 bring it on give Clair Giratina for all I care I just want the first play through to stay true to the original G/S/C.
BTW for those hoping for better names on the US version, Nintendo of America Trademarked them so....
Seems there was 1 minor change between gym leader rosters between FRLG RBG Giovanni in FRLG has 2 Rhyhorns instead of a Ryhorn and a Rhydon like he had in RBG, so at the most maybe we will see some evolution definently nothing beyond 2nd gen though, like Falkner having a Pidgeot.