Iconic characters =/= Strongest characters .
They are the strongest characters, almost every other character has been a variation of those two. They are also the most popular. Which makes it a no-brainer that if Trek comes back to TV, it will feature Kirk and Spock.
I'm not doubting that possible outcome at this point, but their are tons of characters, like Picard, who were made to not be another variation of Kirk, but I'm not starting a Picard vs Kirk character fight. I think I lost you in your meaning of the word strongest. If you're saying the companies strongest, then yes. I thought you were saying the strongest character role. Kirk is a hot headed smart space cowboy, which is why I like him, but the character has been done.
If instead of the reboot they made a post Dominion movie, same story, new crew, Enterprise G 20ish years after a mysterious lightning storm in space ship destroys the Enterprise F (with no other tie to previous stories), 2009 Trek budget and effects, and it turned out it was 27th century Romulan that destroyed Vulcan, and Nemoy's Spock pops up because it was his blackhole theories that doomed Romulus (told to him by Nero), and he runs into a marooned hotheaded commander (kirk-like), along with the other past blackhole scientist (scotty-like), and Spock believes the half-vulcan running the Enterprise G is emotionally compromised, and so on with that 'something starfleet lost premise', IMHO, They would have made the same amount of money. It would have been new and epic and 3D upcharged rewatchable.