it'd pretty much kill the network -- or at least severely hurt it, so if you're at 1.6m subscribers at $9.99 ($16,000,000 / month give or take) you'd need at least that amount * 12 (for the year) to even consider it, imo. Not to mention you're also looking at WWE adding more commercials to a televised WM, so they get that money too.
If someone's willing to pay up a large sum of money that would surpass network revenue for the entire year, I don't see why not, tbh. Would be painful to watch with commercials, though, more so than they already have of their own.
I read that the subscriber number is at 50% of where they wanted it to be by now, so if you're looking for the quick buck, do it. If you're looking to keep the network up and running and as a long-term stream of revenue, don't do it, because once you put it on television, why would people want to keep subscribing? And what happens if WWE loses value and people don't re-subscribe for WM? There's pros and cons on both ends.