Confirmed with the ATM MAE's Product Manager, Caleb Williford.
There will be no connectivity between the "legacy" FDDI MAE
and the new ATM based MAE.
Current FDDI users will most likely pay for FDDI MAE connections
for quite some time in addition to their new ATM MAE connection during
transition. WorldCom/MFS is supposed to be "looking into incentives to
migrate FDDI customers to the ATM side, (see below from Caleb Williford)