Let's not forget that the Raptors won 56 games, made the Eastern Conference Final and took that series to 6 games last season.
Whilst Biyombo, Johnson and Scola are players Toronto probably would've liked to keep, it's not like they are big impact players in the league. What Toronto has gained and retained is a team with several good, relatively young players who could be even better this season with experience, and if even one of the draftees or walk-on's can be a sleeper and perform well, Toronto has a good chance of establishing themselves as the 4th best team in the league, especially with OKC now crippled.
With that said there are several teams with the potential to crack the top four alongside GS, Cleveland and SA. Aside from those I have already mentioned, Atlanta can't be counted out, especially not if Dwight can rewind time to his Orlando days. Memphis have signed Parsons and only lost Barnes, whilst Ennis also had a great bunch of games for NOLA towards the end of last season. Perhaps Houston's overhaul could also pay dividends, as Anderson and Gordon are both solid jump shooters, whilst Harden can be an MVP candidate if only he were to put some fecking effort into his defence.
A lot of ifs and maybes floating around the league ahead of the opening tip. Going to interesting to see which of these ifs can turn into a reality.