While Federer, Djokovic, and Nadal are all still going to play in the next one or two years it's clear that tennis is heading in a direction without the big three. It's an inevitable thing in sports that age plays a factor and tennis is no different. There are many young players ready to step in with Medvedev recently saying that Zverev, Tsitsipas, Thiem, and himself might form the next big four in the next several years.
It's a very nice proposition for fans of those players yet tennis analyst Patrick McEnroe thinks it will be an issue for tennis in the long-term. It's no secret that tennis fans have been spoiled due to the quality they have been seeing for close to two decades and the analyst already sees a change. Speaking on it he said:
"The biggest problem with tennis, if I put on my old USTA cap, is that let's be honest, these young people don't advance tennis the way their elders did. They don't sell as many tickets in the first week of the US Open as Rafael Nadal, Roger Federer, and Novak Djokovic”
It's been quite evident this season where he had several big events without the big three and the tickets sales dropped considerably. The Indian Wells Masters final between Norrie and Basilashvili drew a fairly small crowd considering the popularity of tennis in the Coachella Valley.