Every company can create their own miners and mine. Or sell. Or whatever suits them the most.
Wtf does "they won't be using the available miners" mean? They can use whatever the fuck they want.
What do you think Bitmain is doing? Do they sell all the miners they create? Huh
Wall Street and the Nasdaq companies are going to list on cryptocurrency exchanges, they can and they should include the current mining community, because they will take the entire cryptomining market for themselves if they don't.
Competition is good. Nothing to worry. More companies = more decentralized mining. Even if the only miners were corps, more companies joining to the party = more decentralization between the companies. Some of them will eventually sell their products to the home users.