"Taking back the flag" already gets floated from time to time by actual leftists. The idea doesn't take off because they don't really care that much about flags.

Good Idea unfortunately now that you posted it the otherside knows it.

Ideas get destroyed or stolen when made public

im not an expert but imo, unlikely to succeed, left crowd is young, and dumb, and often broke, more likely to steal than to buy, and the left has them convinced theyre on the "fuck the system" side of shit.