I think this is a very likely possibility. After Megyn’s feud with then-candidate Donald Trump during last year’s primary season, NBC couldn’t wait to sign her. They thought they were getting a real superstar who would send their ratings through the roof. Instead, Megyn has been a major disappointment to say the least. Since NBC is now stuck with the huge contract they gave to Megyn, they just may move her into Lauer’s spot in an attempt to get some type of return on their investment.
It depends on what her contract looks like and if it gives them any way to get rid of her.
I think it's more likely they'd give her a few specials (a Barbara Walters kind of thing) and move her over to MSNBC or CNBC or late night or weekends.