The first Top Gun was a big hit for mainly one reason, the jets! The thrill and experience of fighter aircraft in flight up close was captured.
The next Top Gun that is due out next June will likely be a hit too as it has more jets and better scenes and cinematography. Another big difference is unlike the original all of the cast playing the pilots actually will be in the jets as they go through their takeoffs, landings, and high performance maneuvers and the camera is going to be in their faces.
The actors that were cast all had to go through qualification and testing to be sure they were healthy enough both physically and psychologically to withstand the physical and mental stress of actually enduring the G forces and mental challenges of high performance flying.
Assuming Maverick was in the Navy at least 3-4 years at the time when the events in Top Gun took place in 1986, there is no way in hell some ~40-year career fighter pilot would exist, especially as big as a fuck up as Maverick was, Hell Goose's kid could be up for retirement at this point if he joined at 18.
They're gong to have to come up with one huge mother of a McGuffin to explain away this plot hole.
And if they don't dust off Kenny Loggins to come up with another hit of a theme song, they're doing it wrong.