Djokovic, Nadal and Federer are to long on the top and people wants to see new players on the top.
They are still young and need more experience and stability but they will come on the top eventually, in a few years.
I do hope that Medvedev will continue his strong showings, specially on a bigger stage. We have seen lots of potential players to really challenge the "Big 3", but all of them came short when they are in a Grand Slam that's why the Djokovic, Nadal and Federer continues to dominate the tennis world even at their age. If Medvedev goes on to win the US Open, then I would say yes, so it will be very interesting to see how he will do in this year US Open. Do I really wanted to see new players coming up? Definitely, but they need to prove it by winning the big tournaments in tennis.