stake n shake is a corporation, if they saw that they made good money from Bitcoin, their shareholders will push for for adding all shitcoins, just like Coinbase.
The holding company is called Biglari and it's a public company, ts pretending to be an American company but it's actually a global company. They have no loyalty to Bitcoin, but only loyalty is to maximizing profits. Frankly I'm surprised they didn't add a merchant like Coinbase, which would allow them to accept as many shitcoins as possible right from the beginning.
I have no loyalty to any corporation and all of these global corporations will not exist once we are fully on a Bitcoin standard. We are going to back to local businesses, not global corporations.