PN,
Unless they are supplied wholesale as in Vietnam they could soon be shot out.
It is my understanding the North Vietnamese were out of stock of SAM's at the end of the War when the B-52's went to downtown Hanoi and other hi-value targets.
The Buffs lost quite a number of aircraft in the process but in the end they pretty much had a free hand with not much resistance.
That encouraged the North Vietnamese to get over what shape the negotiating table was and them do some serious bargaining.
http://www.airforcemag.com/MagazineA...linebacker.pdf