Pretty sure Samsung's 8nm has nothing in common with TSMC's 7nm, so it have to be a major redesign.
So unless Nvidia stared the porting process at least a year ago and taped-out months ago, I find it very unlike they will move GA102/GA104/GA106 to TSMC.
Now, they may have realized that Samsung's 8nm was cheap for a reason over a year ago and decided that for mobile GA106 had to be TSMC, but then they are now at the back of the queue for TSMC although a few less GA100 wafers should theoretically produce lots of GA106 parts.
For what comes after Ampere (Hopper?), maybe they will go with TSMC even if JHH likes to moan about cost per transistor all the time.