The other PI assignment policies that have been proposed either require that you have a /19 already in IPv4 (lots of hosting companies don't have anything this size), or have tens/hundreds of thousands of devices.
It has also been suggested that the simple presence of multihoming should be sufficient justification for PI space.
Current PI policy in the ARIN region is /22 for IPv4.
Even if a hosting company does get a /32 or a /44 or whatever, the "you can't deaggregate your assignment at all" policy rules out having multiple independent POPs unless you somehow arrange to get multiple allocations(which isn't possible now).
People have done creative things with tunnels in the past. The widespread existence of MPLS backbones makes that even easier. You will always be able to find one situation that simply will not fit a given policy. Regardless, we still need to have some reasonable policy that creates a level playing field, does not unecessarily restrain trade, and creates possibilities that smart entrepreneurs can exploit to expand the network.
Another option is to create separate ORGs for each colo and get an allocation for each ORG. Owen -- If it wasn't crypto-signed, it probably didn't come from me.