They're still incredibly valuable, especially with the wealth of talent overseas now that's 'hidden away' to an extent. Flip isn't an idiot. People keep ragging on him but he's done the correct thing here and waited to see what EVERY option was before pulling the trigger.
He's about to turn an expiring guy who wants nothing to do with the Wolves into a potential top 5 NBA player. We don't know if flip wants established players- for all we know he planted that to get the C's to give up more than just picks. Taking established players also allows him to try and use Barrea and Martin and his scrubs as pawns in all these potential trades.
If he can dump their overpaid guys for solid veterans on shorter deals while acquiring the number one pick then he's done the ULTIMATE job in paving the way for the Wolves future.
What's also important is that he already has Rubio and Pekovic. He probably wants to keep Rubio and doesn't want to scare Rubio off with a potential tank/rebuild coming up.
Now that Wiggins is on the table (which he never would have imagined before the draft lottery), he's had to think about the long term picture now that he's got Rubio, Dieng, shabazz, GR3 and now potentially wiggins and Bennett.
Seems like he's decided that Wiggins locked up for 7-8 seasons is worth gambling on Rubio staying long term too. He'll be able to convince Rubio that he can now pay him a monstrous deal while developing plenty of surrounding talent on rookie scale deals.
If Rubio wants to bail then really it doesn't matter because he's VERY replaceable.
Flip's done a tremendous job in all this negotiating, and all he's done is control the process and pried his leverage as much as he can- just like Danny Ainge would do.