Rental can pose problems – but how does the shul keep the lights on? The old architecture is not energy-efficient in any way and the heating and AC bill must be nightmarish. If they can rent it out as a hall that is always best – a second kehilla does result in problems at times even as a renter.
Regardless, there is no reason for a new, alternative shul to start with a huge building. That is a recipe for failure – it means they will have to depend either on a big organization (unlikely in BP) or a big donor (more likely) who will in the end want things his way – and that means his rav and his hashkafah.
The best thing is for a grass-roots shul to start small and build itself up from the roots. Alternately, someone needs to find another Lipa in BP – that is a businessman or professional who is not a rov but can take care of the gashmius of an informal shul at least in the beginning. Someone like that can keep it open to all who are interested and let it develop as necessary because he himself is not a rov or a representative of any organization.