The mainnet launch news will make the price of Tron increase most likely but after the release it is going to be a big dump as it always happen with the main net launch or fork news, no matter what project good or not, people always sell after the launch, as people say "buy the rumors sell the news", so for Tron holders the main net will be bad for the price in the short term but in the long term is going to be good. Tron being running his own blockchain will bring good things to the project which will be reflected in the price eventually.