Financially Brian might be better off tourism under the BBs' name… for the first week or three. Then the gigs would tail-off - he just couldn't undertake the same number of shows as M&B, and the touring legacy would wither on the vine.
Why would he want to even go there, though? All signs are to me that he's happy in his new role collaborating with the more creatively active faction of the guys who were once BBs, and with a bunch of young contemporary artists.
Mike and Bruce slogging it out along the back roads of the US and beyond means he can conduct his creative indulgences without keeping a worried eye on his bank balance.
Brian Wilson is and always will be the soul of the band but that's because of his legacy. BW the contemporary creative hardworking guy is his own man.
There is zero indication Brian ever has wanted to or would "take" the license and tour, without Mike, as "The Beach Boys." The only time in the last 20-plus years I've ever seen Brian indicate he wants to tour as "The Beach Boys" was in 2012. Had he been able to continue with the full lineup, I think we would have seen more BB shows with Brian. How many more I have no idea.
As for Brian's "bank balance", while it's all relative, we did examine this in as much as detail as one possibly can some time back in some other threads. While the licensing fee Brian and Al (and Carl's estate) get is likely a nice chunk of change for doing nothing, it is not, relative to the income generated from touring, some sort of HUGE amount of money. Brian and Al would make far more money actively touring and getting a full equal percentage off the top. Brian and Al made FAR more touring in 2012 than they have off their cut of the licensing fee in 2013, 2014, etc.