I actually would like a FRLG remake, as long as it had a major, major overhaul and it included the Sevii Islands. I found Kanto to be really boring and honestly just plain old remaking it in the new graphics style would be really boring as well =/ I'm not sure about a sequel, considering that HGSS is sort of the sequel.
I don't think any major changes would happen, however, as it's considered a "classic" and I doubt that if they re-released it they would want to change the nostalgic feel.
With the release of RBY and the ability to transfer those Pokemon to Sun & Moon I think we can consider those a "remake" of sorts, as the Pokemon can be transferred for the first time and it preserves the nostalgia, everything they probably wanted. So I don't think we will get one anytime soon.