Honestly? I'm can't see how they could pull it off. There's enough (probably a majority) of the BDs crowd that are really only there for Levellers and wouldn't be interested in anything else (or perhaps more fairly, would see the turning of the page as being a suitable time for themselves to move on to new things). So without Levellers you'd need to replace a majority of the crowd which is a tough ask. Probably can't do it gradually in this case, and would need a pretty special lineup to do it in a single year.
Can't personally see a scenario where BDs exists without Levellers as an anchor (using that word in both positive and negative senses).