I was reading the other day an article in Airways all about Jetblue. They are doing very well, they seem to be expanding network and fleet and as you know Jetblue's future fleet plan is exclusively the Airbus A320 aircraft, at least for the near future. But something in Jetblue's profile caught my attention: at the request of Jetblue, Airbus is going to make an A320.5 which will simply be an A320 with two extra rows in the main cabin, don't you think this variant should be named A320-300? I really think so. There was originally the A320-100 which wasn't produced in many units, then the A320-200 which is the current variant in production today, so logically the next variant should be the A320-300. Maybe they mean it will fill the gap between the A320 and the A321, but to me A320-300 seems to be a more logical move than A320.5.
In Jetblue's computer reservation system, if the aircraft is an A320-300, the abbreviation would be 323. If it's a regular A320 then the abbreviation is simply 320. The A323 doesn't exist so there will not be any confustion at all.