In a discussion with Motherboard, attorney Louis Tompros notes that some of these requests have already been successful. Amazon has pulled books that were clearly profiting from Pepe without permission, while Google yanked an Android app that used Pepe for achievements (Apple doesn't allow the use of Pepe in apps). The trickier part is getting individuals like Cernovich and Spencer to comply. After all, they've wrapped many of their messages in Pepe memes (Spencer even uses the frog as his podcast mascot). Tompros says his team is ready to file lawsuits if people ignore the cease-and-desist notices, but he's hoping it won't come to that.
The campaign is bound to rile a lot of people, and not just "alt-right" supporters (Furie and his lawyers know they could be targets of coordinated harassment and threats). Furie would be wielding his digital copyright power in part to express his opinion, much as Campo Santo used the DMCA to object to PewDiePie's racist outburst. However, it's likely that Furie has a solid legal standing here. There's no question that the "alt-right" is copying and modifying his art without consent, sometimes while directly profiting from it. Like it or not, it could simply be a matter of time before Furie gets the upper hand.