Jurassic World 2 (or technically Jurassic Park 5) is only 3 years away, and Trevorrow is indeed writing the script. Though he is opting not to direct because he believes franchise movies deserve a "fresh take" with each installment. It has been said that Trevorrow will hand pick the next director and he personally mentioned possibly looking at Spanish horror directors for the next one.
Besides Trevorrow returning to write the script, both Chris Pratt and Bryce Dallas Howard are set to return. Can't wait!