I see no reason why different musical styles should not be attempted in one performance.
I remember a trio of young lasses in Newcastle who used to sing acapella versions of whatever took their fancy on the last bus home on a Friday night.
This included a medley of I Will Survive & Cushie Butterfield which I really,really wish they had recorded.
That is valid, the music belongs to all of us & will be whatever we make it.
It will survive.