I wouldn't read anything into what Casey said about backup PG and grizzled veteran. It is literally the same exact thing he has been saying since he got to Toronto. I think he believes if he keeps saying the same shit in the media then maybe Ujiri will do it. A perfect example of how contradictory Casey is being to Ujiri is when Casey said he thinks the team is young enough and needs to get older, while at Ujiri's press conference he said how important it is to have a bench loaded with young talent at the 2nd and 3rd slots at each position. Now that doesn't mean Ujiri won't go that route, but I wouldn't take Casey's comments as an indication of anything Ujiri will do.
I highly highly highly highly doubt Derozan has anything near the value of Gay around the league. His contract is less per year, that is literally the only thing Derozan has on Gay. Gay's contract is shorter, and he is leaps and bounds the better player, and everyone around the league knows it. Cleveland or Charlotte could sell Gay to their fans as a young All-Star caliber starting SF that could be a mainstay on the team for years to come. You can't do anything like that with DD. You'd just get questioned on why you traded for a mediocre player that is locked up on a somewhat pricey deal for the next 4 years. Basically, players of DD's quality are fairly common in the league, whereas players like Gay are rare commodities.
I don't know if one, both, or none of Gay and DD will be sent out, but I'm sure that Gay will bring more in return and is much more sought after by other teams.
I don't think tank is the right word for what Ujiri might do. He will build, but I expect that building to involve losing more games this season than we did last year due to an influx of young talent and draft picks, not because we're purposely trying to lose. For example, if we traded Gay for the #1 pick this year and a future 1st then I would not call that a tanking move, but a building move. It just so happens that building move wouldn't result in more wins this year, but will in the future. That also shows control of our destiny (trading Gay for known picks), as opposed to just playing Aaron Gray and D-Leaguers and hoping we luck out into the #1 selection (no way in Hell Ujiri does this, sorry Tim. W).