The cards are bloated and on par with what used to be regional promotions for the most part. Many of the big names have either retired or been injured.
If a new org were to start up and could attract some name fighters, pay them well, and deliver good solid cards for less money than the ufc is charging............
Youre damn right they could be challenged.
That's all a new organization has to do?
If it was that easy, someone would have done it by now. Many have tried but they failed miserably.
The UFC has all the big name fighters right now so a new organization would have to get some of those guys to leave the UFC and sign with them. That means they have to overpay the fighters to get them to even consider leaving the UFC. I'm pretty sure the UFC has the right to match offers so the new organization would have to pay the fighters so much that the UFC would decline to match.
They would also need to deliver a good solid card like you said so they can't just have one big name main event and then a bunch of crap. They would need at least 5 good fights which means at least 10 good fighters for each event.
Then on top of that you're saying they would charge less money than what the UFC is currently charging. Something tells me severely overpaying fighters and then charging less for the product isn't going to work in the long run.
A new organization successfully pulling that off and competing with the UFC is completely unrealistic.