"Jackpot" is a really weird way to put it and you make it sound more complicated than it actually is.
I'm quite sure that what you're suggesting here is pay to enter "winner takes all" tournament. It's pretty much a casual tourney, just like the ones we already have, but with additional hassle and risk of losing your money. Yeahh I don't think there is really a need for that, unless the stakes are high (like 5-20k to enter), then I can see how some people would be interested in it. But then again, duel offers much better odds of winning, so I don't see how this would be superior.

Edit: I think it's also worth to note that opt in tourneys have been suggested many times and it was denied so I don't think it will be different this time