So, any alliance will want its members to contribute something. For many this likely means having capital ships and the battleships to support them or being an industrial power house.
However, I think, for alliances with smart leaders, there will be the opportunity to attract small entities focused on say Planetary Interaction products into their alliance. To me, this seems like a great place for a small, focused, corporation (1-5 players) to contribute to a larger effort.
If I was going to pitch such a corp to joining a sov holding alliance I would first look to 1) demonstrate pre-existing POS fuel product chains in low-sec and 2) that the pilots have the necessary skills to support such an an operation.
The small corp is not attractive to the alliance horde commanders, but they may be useful to an already overstretched industrial backbone, especially if it is able to operate somewhat independently.
Just ideas.