With the way NJPW is struggling right now with money issues, it wouldn't be a bad idea for WWE to go after Okada and then promise him some type of international executive role down the line to get into the Japan market. He could legit run some type of indy promotion there and the fans would probably go since it's Okada.
But do I expect that to happen, no not really. I expect him to take TK's money and have a couple 'dream' matches a year.
Tenryu did that with SWS-WWF and it did not work, and that was when new promotions were coming up left and right and most caught steam right away.
An Okada-led promotion needs to shut down at least two or three other indys (NOAH included) and instantly become a "big thing" for it to truly work. The puro business is too much in the shythole for a new promotion to get things going without reducing the market and consolidating talent.
Now, a 1 time show? Sure, that could be a big success if booked decently with Okada leading it. But a promotion is a whole different ballgame, it would take a big ass operation which I'm sure WWE would be willing to pull off, but I'm not sure Okada would.