End of the dynasty. Golden opportunity for the rest of the league
Not necessarily. KD looked like he was gone. Now he may be back. They just need to get some injury protection in his contract. Assuming he comes back and shows he's reasonably recovered, they could get a nice return by trading him.
Klay's ACL injury is not really concerning. Recovering from ACLs is common place now Klay shouldn't be affected as much as other players whose game depends on their athleticism.
Taking a step back for a year and ending in the lottery isn't a bad thing. Gives them an opportunity to get some new blood in who might extend their dynasty.