Styles of play definitely come and go, and whoever manages us (Wilder or otherwise) will have to adapt over time, evolving the tactics. However, I do see our current approach as more than just the flavour of the month.
Seeing how capable and threatening we look against some of the best teams in the division, while having a modest squad makes me think that Wilder and Knill are on to something big. Maybe it's just our players playing out of their skins, just a purple patch, but if it's more than that we may have stumbled across the next Gegenpress, Tiki-Taka or Total Football.
The above might be a bit of an exaggeration, or a case of me wearing rose-tinted specs, but I still have faith that there's plenty of longevity in the approach and even if teams begin to "figure us out" or emulate us, we still have the head start.
Also, Wilder's approach to man-managent, his standards/expectations and his ability to motivate aren't as common as the should be at the top level. I feel that an understudy to him, someone who's experienced playing for him may have a better chance of maintaining these standards if he left, rather than a completely new face with a new approach.
Long story short: Chris Wilder is the next Cruyff, and we're the next Barcelona.