I'm thinking we'll see Widow next, because it as been a while since her figure was released. After that one of the other characters who already had a figure. Maybe Thor or IM. I have a feeling it's too soon for the new Cap yet.
Then we'll see Hawkeye, a whole new character which has to still prove himself in movie form, so he has to be released when the hype is at it's highest. After him we'll see either IM or Thor (depending on who was released after BW). Then it's time for the new Cap and after that we'll get the Hulk.
That's how I see it at least.
Also I'm kinda hoping that HT will skip the Thor Loki and move right on to the Avengers one. He looks a lot more awesome I think.