You're suggesting that the Clippers wouldn't have worked out any contigent cap-clearing deals for Gallo's contract between now and July 1st?There were no teams with $23 million in open space at the trade deadline. And the Clippers didn't unload him then (mostly because they literally didn't have the picks to trade until after the Philadelphia deal). So, sure, they could spend the early days of July that the competition (read, New York) are using to aggressively court Irving and Durant.
Or, you know, they could just deal their backup PG of the future and a middle first to the team that Kyrie plays for to land Irving in a sign & trade and sign Durant outright. Because between Williams, Harrell, Zubac, et al, they already have a pretty good surrounding cast of roleplayers for their stars.
I'd like the Celtics to get solid assets if Kyrie leaves too, but this feels like wishcasting. SGA would be one of the most valuable S&T pieces given up in the past 20 years, and all the Clippers have to do to avoid that is work the phones a bit for 2 months.