If the stories about Tosh Raka in the Mysterious Akavir are true, do you think that it's possible that the Khajiits will likely view him as some kind of avatar of Alkosh should he invade Tamriel?

Maybe.

More likely if Tosh Raka's dragon form also has Feline aspects about it.

Maybe we now very little about Ka Po Tun unlike Tsaesci the only mention of them is from Mysterious Akavir

I guess he would inspire awe in the Khajiits. It's very likely he's yet another identity of our cuddly multiple-personality disordered Akatosh.