If you are going to play it competitively in tournaments, or plan to run a huge man tournie, this game is going to get sales. Its cheaper to run tournies without the worry of having DLC or not by getting the full disc form.

I am pretty sure theres going to be DLC for CSII users though, theres not much reason not to with them paying for the previous characters. I don't think CS Extend is going to have much difference in story either.