Victoria and her mother were both heartily against marrying her cousin George, Cambridge's eldest; it wasn't going to happen. Albert's brother Ernest is indeed the next most plausible candidate, but what I've read of them suggests they were rather different people - it's likely that Victoria wouldn't like Ernest. If she manages to make it to the throne without getting betrothed, it could be anyone - my guess is she marries later, and probably to some minor member of the British nobility that Melbourne steered towards her. Britain doesn't need a continental monarch for a Prince Consort, and had Victoria not found Albert so personally entrancing it almost certainly wouldn't have had one.