Yeah, this one could blow up in our face if we fail to do a deal and we lose Glen Davis and Delonte West and get minimum wage veteran leftovers.
Then we would be looking at a February fire sale and 5 years of struggling to acquire talent.
chances are that even with rondo next year, you are gonna struggle to acquire talent. so why not go all in for paul and see if you can luck out with howard etc for example? it's high risk/high reward. and if paul does come and leave at the end of the season, well, you have a boat load of cap space and you can literally start from scratch (be bad/lottery/get high picks/luck out in drafting a durant/lebron/d rose type talent).
but that's a false premise. sure, with only PP and either JJ or Avery on the books and assuming they've waived the rights to KG and Ray to make cap space, there's money to be spent. However, have you looked at who's a FA that year? It's CP3 (who'd be elsewhere in your premise), DH (who's assumed to be following CP3 wherever and if not, he's most likely not coming to Boston) and Deron (who's likely to resign in NJ and if not, is very unlikely to go anywhere but Boston). No one else plays at a level that would even generate thoughts of a max-level player. No perennial all-stars either. The restricted list of prospects is ok but they'll most likely be matched by their current teams.
Also, don't forget that the team will have most likely sent out at least 2 first rounders and most likely one will be the 'prized' one we're getting from the Clippers. There'll be even greater difficulty in rebuilding. Throw in the fact that are current trading chips of Ray's, JO's and KG's expiring contracts will have expired (and we would have renounced the rights to resign them to get that cap space you mentioned) so we won't have anything of value to trade either.
don't let the FA market from last year lead you to believe that's a common occurrence. It's highly unlikely that the FA market will see that level of available talent anytime before the next CBA is agreed to.
In short, if Danny pulls the trigger for CP3, he'll have given up so much of our assets that if CP3 walks after the season, we're screwed for years because we won't have talent on the team, won't have many draft picks in the coming years nor will we have expiring contracts to deal for talent or picks.