Even if Evan Longoria doesn't get the bulk of his extension, which makes him 'relatively affordable' to trade now, he's still a multi-millionaire. He's still got a long term deal with the Rays and he's been an all star. He's got value and the Rays appear to need help, so he's likely to be moved at some point.
Apparently Evan Longoria is upset that the Rays traded Logan Forsythe. The franchise can not afford to keep all of its stars and must always plan for the future. However, his career is in an area that is always changing, and he needs to appreciate some risk. Exchanging Logan Forsythe to the Dodgers fir Jose De Leon COULD be the best thing that he ever agreed to.
Baseball players are paid an exorbitant amount of money to play a game. With little or no education or alternative skills, they will become very wealthy. The big money that funds Major League Baseball demands that every team build toward winning, trade if they must, and eventually win. It is very simple - win or get fired or traded.
Even great players get traded sometimes. That doesn't mean that the person isn't a great player. It's just one person's opinion, or the opinion of one club. Players get traded around during their MLB careers. That is just what happens. He shouldn't be disappointed because he's lucky to be in the MLB.