It is highly unlikely that a big pharma player would want PTX. Their branded products are simply reformulations of existing drugs, most of which already have generic equivalents. Smart payers design their formularies to avoid the expensive knock-offs from companies like PTX and steer patients/docs toward the generics.
The PTX generic portfolio may have a bit more value, but even there, they are not selling generic equivalents of blockbusters. Their generic portfolio is a bottom-feeder strategy that targets smaller drugs that don't get the attention of big generics.
In this strata of the pharma industry, the best you can hope for is some "trash-trading" of companies or portfolios among players of the same stripe. PTX's acquisition of Somaxon and Cypress are perfect examples of this. However, even if PTX is able to court another third-tier pharma player to buy it out, it will not be at much of a premium.
Best case: PTX finds a buyer to take them out slightly above their current value. Worst case: PTX ends up in bankruptcy. Mid case: PTX continues to muddle along, losing market share and ends up trading on the pink sheets indefinitely.