Yes, if they are to remake Gold and Silver, they would have to include Kanto. If they don't, then it would just be a spinoff. Oh, and if many of you guys haven't noticed, Crystal will most likely not be remade. Why? Because, when Fire Red and Leaf Green came out, Yellow version was not remade. If they did, it may of been called Thunder Yellow, anyway. If they did remake Pokemon Yellow, it would mean taking a step backwards threw time. See, Pokemon Leaf, Fire, and Aqua are remakes but also spinoffs. In Fire, Leaf, and Aqua, you live in a time period different from Red, Blue, and Yellow, also Gold, Silver, and Crystal. Well, in each game (Yellow,Crystal, and Emerald) certain things happen in that time period that can't and wont happen again. Examples: Yellow: You caught mewtwo, and the house below Fushia City appeared. (notice how this is kinda following the anime series (except for the catching of mewtwo)). Crystal: The sighting of Suicune, battle, and capture of Suicune and Battle Tower apeared. (again following the anime, except for the capture of Suicune). Finally, Emerald: The precursers of the fight against Groudon and Kyogre, the appearance of Rayquaza, and Battle Frontier appeared.(know I didn't really watch the Hoenn series of the anime, but I know Battle Frontier was in it).
Ok, so know I've shown you three examples of why Yellow, Crystal, and Emerald can't be remade. Beause that would be altering time, but thats why they made a remake-half-spinoff of Red, Blure, and Green. All your doing in Leaf, Fire, and Aqua are revisiting Kanto at a later date. So I cant see why not, why wouldn't they remake Gold and Silver.
But there is a way to make a spinoff of Yellow, Crystal, and Emerald. And it might occur when the game after Pearl and Diamond come out. But I not going to say anything, I'm just going to wait and see.