Jim. for sure MorphOS should (and will) be based on MorphOS. But looking to alternative solutions may help to make thr right decisions. Evaluation of these solutions will give a vote on what to do and what not to do.
As far as I know the history and the developers I ampretty convinced they will not go for a Linux base. But if they eventually did, it would not be the end of the world or MorphOS would instantly beome YALD. It could stay pretty authentic.

That said I vote for not using a *nix kernel or an other alien kernerl, but let Laire et al do the real hard job themselves