Problem is with fighters getting international visas & finding an amenable commission.
Tribal venues are ideal right now because they're within US, largely solving the visas issues, and UFC has enough money to make them bend the knee.
Right now, even if, say, the Montana commission would sanction a fight, UFC risks the governor coming in and saying nope. This isn't an issue on tribal land. If Dana truly wants this, he'll get it done, in large part because his underpaid fighters cannot afford to lose a paycheck and won't say no to fighting under however dire these risks and warnings become.
Hard part will be convincing the top talent who headlines the cards. Enough of those dudes can afford to wait on the sidelines for six months, it will be hard to maintain top talent at the top of so many PPV.