You know. Actually, keeping Asuka undefeated for years would be so cool to see. 2 or 3 years. It would give modern fans a taste of 70s wrestling. You could move her to Smackdown and just revolve the entire division around her. I know it would get tiresome really fast with the modern schedule of monthly PPVs and weekly shows, but it could work if you do something similar as they did with CM Punk. Turn her heel down the line.
Nobody wanted Punk to drop the belt to The Rock after 434 days. Nobody was tired of him. I believe Punk could have lasted all the way until Summerslam 2013 as a champion. Fans still wouldn't be tired. That's 200+ more days. 634+ in total. That's around 2 years. Asuka could do the same. Start as a face, turn heel and then maybe turn face again at the last months of her reign, before finally losing to a big opponent in a big match.