I'm excited by the idea of new models. But as someone who just picked up the game a few months ago, I'm also dreading it. I haven't gotten a lot of use out of the models I already own. If new Crisis Suit models are released, for example, I'll feel tempted to buy. I was looking forward to a short period of time where I had 2,500 points and didn't need to spend a lot of money on models for awhile!
(no one ever reaches that point, though, right?)
I know I can use the existing models - they don't go out of date and don't become illegal. So it's my own fault if I feel pressured to buy newer ones.
Don't worry, crisis suits, broadsides, fire warriors, drones, hammerheads and all the specialty suits will stay the same, as they were updated or released relatively recently, if we get new models for existing units, it will likely be vespid or kroot, more likely we will get new unit, my money is on either more kroot or demiurg (I kinda hope it's not demiurg though and we get different way of psychic defense then non-tau models)
We might get new character model though, and I am really hoping we get non-T'au sept Longstrike, as this is something I really dislike about the current keywords, if you want to play tanks, you need to play T'au sept, also it's about time longstrike's suit is put into production for other septs