Longer term, the budget in the DAO will grow and we can do more with it. Because of the ongoing process of HIVE being converted into HBD and becoming usable in the budget.

There is also the blocktrades proposal for a conversion function, or something like it.

Could conversion be done with a pool? Probably. It would need to be designed, rules defined (how you put in, take out, etc.) Likely possible, but without a specific proposal with all details filled out I can't really give an opinion.