I think the people hoping for another year of tanking and a high draft pick are going to be disappointed. Just based on who they have now, and the change in coaching, I think it's likely the Raptors will improve substantially.
One of the things the Mavericks were especially good at all this year and in the playoffs were playing their best, most efficient lineups. They use in-house +/- metrics to help decide what these lineups are. We don't have such metrics, but we do have basketball-value, which has +/- data for all the Raptor's 5 man lineups, last year.
First of all, we find that the Raptors likely starting lineup for next year was above average. Calderon, Demar, JJohnson, AJohnson, and Bargs played a lot of minutes together last year and outscored the opposition by a decent amount. This by itself is a big deal: you'll notice that the starting lineup from the beginning of the year (Jarrett Jack, DeMar, Kleiza, Bargnani, Evans) was terrible. Having a starting lineup that is above average, as opposed to one that is well below average, will make a huge difference.
Looking at our bad lineups (i.e. most of them), I think we find several patterns. Most of them feature one or more of the following factors: Sonny Weems playing with Demar; Linas Kleiza (who was playing through a serious injury); or Ed Davis and Andrea Bargnani playing together. Or Jarrett Jack, who sucked for us.
I think a huge problem we had most of last year was lack of an adequate three. Julian Wright looked awesome for us, because when he was playing we weren't trying to defend opposing small forwards with natural 2's, or guys with serious undiagnosed knee injuries. That will not be a big problem for us this year, unless Johnson goes down with an injury.
I think our team has good, winning lineups that it can put out there, even before getting the natural improvement that you expect from Ed, DeMar, and Bayless. And I think Casey will do a much, much better job than Triano of finding those winning lineups and playing them. I don't know how much difference it will make overall, but I very much doubt we will be looking at a top 8 pick in next years lottery.