Boras can get all six signed in the next 37+ hours ... if that's what he and they want.
Probably some of them already have deals struck. Assuming the deals are "above slot", they just haven't turned them in to the Commissioner's office yet. I'm sure there's more than one fax machine available tomorrow night.
As for Strasburg, I would guess the strategy is just to make sure they've completely milked the cow. For $15 m, he'd be a darned fool not to sign -- unless by waiting another 35 hours, he can get more.
Boras has already shown that he will hold a player out, e.g., send him to Indy ball, and let them negotiate the next year. But Indy ball doesn't make you a free agent, it just throws you back into next year's draft, with less leverage I would say. Japan is possibly another tack he would try, but given the economy I don't know that anyone -- not even the Red Sox or Yankees -- would throw Daisuke money at Strasburg next summer.
I'm betting a record breaking deal gets done, well below the posturing figures but well higher than any prior deal.