FWIW when thinking about multiple PHY to a single MAC, what comes to my 
mind is the SIS 900 board, and its driver net/ethernet/sis/sis900.c

It has a function sis900_default_phy() that loops over all phys to find 
one with up-link then to put all but that one in ISOLATE mode. Then when 
the link goes down it loops again to find another up-link.

I guess your series would also help in that case, wouldn't it ?

Yes, it would. However, that driver would need its PHY handling
re-written because it is using the old MII code, not phylib.

	Andrew