Crash Bandicoot (Naughty Dog 1996) = 6.82M
Crash Bandicoot 2: Cortex Strikes Back (Naughty Dog 1997) = 7.58M
Crash Bandicoot 3: Warped (Naughty Dog 1998) = 7.13M
Crash Team Racing (Naughty Dog 1999) = 4.79M
Crash Bash (Universal Interactive Studios 2000) = 3.39M
Crash Bandicoot: The Wrath of Cortex (Universal Interactive Studios 2001) = 7.24M
Crash Nitro Kart (Universal Interactive Studios 2003) = 3.10M
Crash Bandicoot 4 (Naughty Dog) = ???

A comeback from the bandicoot (Naughty Dog as developer) on the PS4 would be a huge thing!
This series is still popular nowadays for example the monthly PSX classics ranking where the Crash Bandicoot trilogy is always in the Top 3. Crash Bandicoot 2: Cortex Strikes Back and Crash Bandicoot 3: Warped should already have broken the 10M mark including the digital sales from the Playstation store.

What do you think how much a Crash Bandicoot 4 from Naughty Dog could sell?
I could see Crash Bandicoot 4 from Naughty Dog selling 8M retail and 10M retail and download combined, the Crash Bandicoot franchise is still huge imo.

Hmm....maybe 2.5-3m LT.

My completely random guess is +4 million.

2M

It depends on how they re-introduce Crash Bandicoot I guess.

Remember how the Sly Cooper games were huge hits on the PS2 and sold over 1m each? Then when Sly 4 Thieves in Time came out for PS3 in 2013 it only sold about 500k. Not saying this will happen to Crash but i'm just saying.

All depends on who develops it and what platforms it releases on.

As an exclusive with a major push from one of the big 3, it could sell 4 Million plus.

As a multiplat, with a small push and likely technical problems? Youre looking at a shit show when it comes to sales.

Developed by Naughty Dog and PS4 exclusive.

Well the OP does say the game would be developed by Naughty Dog.

Probably around a mil or 2? I honestly think Crash wouldn`t sell as he once did. The times where he was popular has passed and he would likely seem sort of awkward in the game space today. It wouldn`t do crazy numbers, but it would do well enough I figure.

I say 1-2 million