You'd be lucky to pull off an all-tag or all-Knockout episode of "iMPACT!" without it flopping, so that's a big "HELL NO" to the PPV notion. You have to remember that the cable shows bring in ad revenue based on a contract, not the ratings. PPVs are reliant on the actual buys and viewership to generate a return and there's no chance that either of those shows would make enough money to justify the cost.
Now you might say, "what if the main eventers were tag teams for a night?" That's a valid point and it could be made to work, but it's very difficult. Going based off the current landscape, would a Main Event tag match of Sting/Angle vs. Anderson/Ray or even Anderson/Jarrett be a draw? You'd almost have to make it Anderson/Hogan to get people to buy, and even then it's a colossal risk because of how many of us don't really want to see Hogan in the ring anymore.
Now for you TNA purists, don't kid yourselves. Beer Money vs. MCMG or even Beer Money vs. Styles/Daniels isn't going to sell a PPV, either. It certainly isn't going to sell it to the level that it justifies putting your top stars and biggest storylines on the shelf for a night just to feature the tag division.
You might argue that if this is true for the tag teams, why isn't it true for the X-Division? Well, there's a huge difference. The X-Division is TNA's traditional trademark. You can sell it's return, and the return of the six-sided ring, as a one-night event to excite the loyal TNA followers. That is something uniquely special about TNA that garners interest and support. Tag team wrestling, while certainler superior in TNA than in the WWE, is not unique. Styles vs. Daniels, with the backdrop of the legacy of the X-Division and TNA's history, is a much more marketable event than the scenarios listed above for the tag teams.