Several factors make the Bills future situation tricky, the largest one being Ralph's age and the impending estate tax when he passes away. The government applies a 50% estate tax upon death on any assets exceeding 1.5 million. If the franchise is valued at 637 million then Ralph would owe 317 million dollars to uncle Sam on just the Bills franchise. That figure does not even include Ralph's other assets which I'm sure are pretty substantial.
Now I'm sure Ralph took a lot of this hit into account with his attorney and planed accordingly. Loop holes can be found to protect assets from the government, I'm also pretty confident he has a substantial amount of insurance to help off set the estate tax.
Regardless of the how well Ralph did his estate planing the sheer magnitude of the estate tax he will face leads me to believe his daughter will be forced to sell the team. What we have going for us is a profitable franchise and a good fan base, and if his daughter can find a buyer who agrees to keep the team in Buffalo we will be fine. I'm sure his daughter will try and honor Ralph's legacy by searching for a buyer who would make this arrangement.
The problem arises if she can't find a buyer that agrees to keep the team in Buffalo. Remember she will be forced to sell the team to pay the estate tax, if she can only find a buyer that wishes to relocate she will be forced to make that deal. It's really not a matter of her intentions, it's a matter of the buyers intentions. The future basically comes down to one simple factor, the person that buys the team when Ralph passes away must want to keep the team in Buffalo.
As a side note I am not an attorney and don't know the specifics of Ralph's estate planing, however I did stay at a Holiday Inn last night.