Heartgold and Soulsilver had some of the new evolutions of old Pokemon that were added in Sinnoh (Yanmega, Mamoswine, etc). So to some extent, probably. In case Spooky's simple reply wasn't to your liking
I have returned, my friends. And I've become more powerful than you can possibly imagine [insert evil laugh here].
They could throw in a few Sinnoh/Unova Pokemon after you get the National Dex like they did with the Hoenn & Sinnoh Sound for HGSS but during the mainstory line I think they will stick with the original Hoenn Pokemon and a few Johto/Kanto ones here and there.
Re: Do you think foreign Pokemon Will be available in-game in the R/S Remakes
Maybe they would add elements of Emerald in Ruby and Sapphire remakes, like they did with HeartGold and SoulSilver, which would mean the Emerald Pokedex, which includes Kanto and Johto Pokemon. They might add a little bit of Sinnoh and Unova Pokemon too.
I do know they would include Gallade and Froslass.
They've been in all other remakes, so... probably. Pokemon is "evolving" in
2013, though, so no one can say if even will be remakes.
I don't think they would disappoint the fans like that