I think you find encouragement in the sheer volume of options that exist at the 5 - Shaq, Krstic, JO, Baby, Garnett, Davis - and that's just as of today. And that's if no one else who can slide to the 5 is brought in.
The "who plays the 5 now?" argument against the Perkins deal becomes a bit of a strawman, IMHO, because of that volume.
And ... there's a very intriquing chance now to go small to close games, as we did in 2008 - Rondo, Allen, Pierce, Green and KG at the 5.