Subscribers will automatically move.
feeds.feeburner.com/URI will
not expire - the plan is that once migrations are complete, it will
map directly to the same server as
feeds2.feedburner.com, and so the
redirect will be removed, because it will no longer be needed.
This is a temporary redirect to move traffic from one data center to
another but after the old data center is closed all traffic will be
routed to the new one.