I honestly think in the next few years you might start seeing more am only tournaments. Of course everybody likes seeing top name pros come into town and destroy their home courses, but the sport is at a weird point right now. There is a push to get more money pumped into pro events so more people can tour and gain exposure so that big time sponsors get involved. That's going to require a lot of work by the TD or whoever to raise extra cash to go towards a pro payout or else you won't draw the touring pros. Ams on the other hand you pay out in merch, so the $15 credit they receive is being used to buy plastic that has a true cost of 8-9 bucks or whatever. That helps ensure that all of the "hidden" expenses get covered and you don't lose money by hosting a tournament. All it takes is a tournament or two where a local club actually loses money and the desire to host more pretty much becomes non existent, especially considering all the effort that goes into planning and promoting the event.
There are definitely disc golf areas that can sustain large professional tournaments, and it's great that they do. I wouldn't be surprised though to start seeing more of a divergence between ams and pros, especially with all of the start up disc golf companies coming out of the woodwork. The am players are where you are going to take your money, and eventually somebody will start taking advantage of that. Dynamic Discs has the right idea, they promote their own tournaments and provide all of the merch and get their name out in the process.