Coachella is one of the biggest music festivals in America, so it's no surprise that tickets for next year's event are already gone. There is some question about whether or not Coachella should move to a different venue in order to accommodate the crowds, but I think that the original venue should be retained. It's the bohemian atmosphere that people know and love, so keeping the location as-is helps that culture to survive.
Nearly one hundred thousand people visit Coachella throughout the week that the festival is put on each year. It would be impossible to find a venue that could accommodate more people while keeping the same feel. A better solution would be to have summer and winter Coachella festivals. This way, people could choose when to attend and get a better chance to see the bands.
Coachella is a huge event in the music festival scene. If the location becomes too small for the amount of people that crowd in there to see these amazing acts. So as long as the great music is there people will still come because it is the music they come for not the venue itself.
The venue itself isn't very relevant, especially considering the number of amazing artists at Coachella every year. It could be argued that adding more tickets lowers the exclusivity of the event, making it less desirable, meaning people won't care as much. But whatever the case, changing the venue would not be the issue.