Well by many accounts they did have a original idea for it which sounded pretty neat, but it was thrown back to the drawing board due to capacity concerns, and the pause from the Covid Lockdown hasn't helped with the development of this.
The original idea was most certainly a complex ride system, but honestly I don't think we're gonna' see that come to life. I'm in the boat of some others feeling they're gonna' play it safe, and safe is using a ride system they already have. I hope that's not the case, but as far as we know it could very well be Flight of Marvel.