I agree with most of what you're saying, and it certainly doesn't bode well that he has been sent on loan 2 seasons in a row - there's not much precedent for players coming into the starting 11 after that. But I personally think he's got the talent to be buck the trend. However, Mane, Salah, Ox, Coutinho, Lallana and Firmino could definitely be regarded as "stiff competition" for the 2 wide positions. To suggest otherwise is laughable.
I would accept an argument that Firmino wouldn't be considered ahead of him, as he really has a specialist position in our starting 11, even though he can play wide aswell. But I think both Coutinho and Lallana can be classified as wide forward options on the condition that one of Mane or Salah is on the other side. Ox has played most his career as a wide-forward, regardless of whether he likes the position.
Kent's still got a chance with us, I'm certain of that. He will need to adapt/improve his game in certain aspects for it to happen though.
However, Mane, Salah, Ox, Coutinho, Lallana and Firmino could definitely be regarded as "stiff competition" for the 2 wide positions.
Of course - if the competition was "which is the better wide player, Kent or ...?". Mane and Salah were already taken as read. Of the other four, at any given moment two or three of them are likely to be playing in other positions. Or, as is the case until November, one could be injured. I wasn't saying that Kent could force his way into the starting lineup any time soon, but that -
if he was considered 'close' - he could get some sub appearances, in addition to cup appearances, particularly if two or three of those six were unavailable for any reason. Hence I suspect going on loan means he's not considered 'close'; which for a player who is 21 in 3 months, I think probably suggests there's not great confidence that he will make it here.
Now there's a wider discussion about whether a player benefits more from going on loan, or getting some (say, 1000-1200 minutes) game time over the course of a season with Liverpool. It should also be noted that - being a selfish git - when talking about the player's development, I really mean development towards becoming a good Liverpool player.