There was going to be a second movie in 1987
I read about these books that came out in the 80's about teen stars, there were a couple of people from the Goonies cast ( I do believe one was Martha Plimpton). With the people's names were a list of the movies that each had been in, and "Goonies 2" was listed by some of their names. So obviously it was supposed to happen.
Also, I read that they had fully planned on releasing the second Goonies in 1987. This was all from a reliable source. I just wonder why it fell through because back then the movie was still new and fresh.