I would obviously love Tellius remakes, but I'm also unsure how much potential there is for improvement. Portability would be great, redone battle scenes and cutscenes with better voice acting as well, and then there are small things like adding actual supports to RD, but beyond that I don't think there's that much they could do, in fact I'd be cautious about some of the changes they'd potentially make, in a lot of ways I wouldn't want the games to become more like modern FE. I guess the big bonus would be being able to even get your hands on the games for a reasonable price at all, but I don't see why that couldn't just happen without fully fledged remakes, Nintendo just have to pick up their slack with their Online service.
Regardless I think we'll have to wait a bit, as I'm almost certain the next remake will be The Binding Blade, just so people in the west can finally experience Roy's game, and maybe that'll transition into a remake of The Blazing Blade too.