I have no clue what he will do.
Personally, I think he should stay for a couple of reasons. First, next year's team will be very different from this year's team, and his role is likely going to change a bit. I think the addition of an experienced true point guard, and an experienced true small forward will help greatly in Royce developing his game even more. If Lucious and Clyburn are as good as we think, then I believe Royce will be a front-runner for national POY next year.
Secondly, there is no doubt that Royce's NBA stock has gone up from the two NCAA games, and probably would have gone up much more had ISU gotten a better seed and a little better match-ups. I just don't know if it moved him into the first round. As far as I know (and I could be wrong) the 2nd round draft choices still do not get any guaranteed money or contract. If Royce sticks around, there is no doubt in my mind that after next year he would be a first round pick, and very possibly a lottery pick. Like others, I think he also needs to work on some aspects of his game, mainly his outside shooting, but I am not so sure that keeps him out of the NBA.
I look at some other ISU players that went to the NBA, and I think the closest player to Royce was Fizer, as far as position, skill set etc. Fizer scored most of his points around the basket, but also had the ability to score from the 12 to 18 foot range. By his junior year, he was a bigger part of the scoring offense for ISU than Royce was in his first year. Fizer even shot 35 per cent from 3 point range his last year, although he only took about 40 shots from that distance. He was not quite as good of a re-bounder as Royce (especially in the NBA), but he was drafted mainly because of his offensive skills. These are what Royce I think still needs to develop more in order to be a high draft pick. That is where the true money and security is. With the players that are coming in and eligible next year, I think he can develop and showcase the skills to be a lottery pick.
I also think that this is an ideal situation for Royce. He has a head coach who is a former NBA player and executive, and who I think will be able to get as good and more realistic feel for Royce's draft potential than any other college coach in the country. Wisely, Royce seems to have kind of left next year in FH's hands. I think Fred will find out what he can for him. I don't think Fred will try and "push" Royce on to anyone, and I think he will give Royce an honest opinion and good advice.