The rental part has never affected a team's ability to get value(picks) at the deadline from fringe playoff or fringe contending teams, even as recent as last season..I don't think the Spurs have any chance of getting a good prospect for Aldridge, at this point IMO..they could probably get better value from a fringe-contender team if he raises his stock by February IMO..his on-court value is literally as low as it could possibly be, right now..
As I said in the other post, though, I hope your source and other sources are wrong about the urgency of an Aldridge trade, but you're probably correct..if they can get a high 2018 1st for him, right now, though, I would do it, regardless of whatever else accompanies it(I doubt they could even get that right now, though)..