Merged mining BU, Segwit with BTC

I put this over in the dev board, but looking for some more general criticism.

Would there be any thing to stop merged mining Segwit or whatever BIP, and use the same address distribution as BTC?

Would this not make a natural outcome as to the best way?

No party has to compromise, you get your preferred unadulterated implementation

It avoids a hard fork, and allows whoever want to mine as they wish to upgrade as they wish?

I suppose updating with say development / innovation over time may be hard if you cannot attract enough devs, and the dev overload on say wallet changes / infrastructure change may be an issue, but still if it that much better good/popular solutions should attract enough of a following.

ETH / ETC shows a demonstration how this to works to some extent.

I think you would see BTC (now), BTU and BTS (SEG) emerge, and each go to their price and utility, no one would be forced to join in or opt out.

It maybe I don't grok merged mining enough to say this but is seems a possibility to at least demonstrate the economic / network case.