They're building for the future, but the time horizon has shortened considerably. If they make the playoffs this year, then fantastic. They may really go for it next year.
The shortened development horizon probably affects the guys who were on the longer development track the most. I mark those as Malaki Branham, Blake Wesley, and Dominick Barlow. They each have promising (or very promising) skill sets, but may not have the same leisure and opportunity afforded Vassel, Johnson, Murray.
Then we have the rescues. Spurs astutely picked up cast-aways Charles Bassey, Sasho Mamukelashvili, and Julian Champagnie. Each is 22-24 years old and cannot be said to be 'development' prospects in quite the same way as the 19 year-olds. But each was stuck on stacked playoff teams where they couldn't find court time.
Last we have Keldon Johnson, alone of the core, although I'll mention Tre Jones, who is an almost 'must keep' due to his position. Keldon's timeline was actually very short, in my opinion. I think he might have been traded by the trade deadline as a 'good soldier' move, getting him to a playoff team. But now that's changed.
Of everyone mentioned:
Malaki Branham has the best chance to stay. His ceiling is unknown but high; only way I see him getting eventually moved is defense.
Blake Wesley will have at least another year to develop. I do think his future is wobbly, mostly because of guards that could get drafted eventually.
Dominick Barlow will get another year, probably.
Mamu, Champagnie have good skill sets. But are they NBA rotation guys? Champagnie seems safe - the team badly needs shooting. Mamu's skill set could be exceptional next to Wemby at times.
Bassey is locked into a remarkably cheap contract for several years and his strength and growing skill set could be very useful.
tl;dr I don't think anyone's out the door at all. But the horizon has shortened on what the team will be able to offer in terms of development and guaranteed roster spots. If the Spurs were looking at the playoffs in 2-3 years without the scads of draft picks, that would be one thing. But they will need to start trying to improve the starting lineup. And they may need to pull the plug earlier on a guy like Wesley.