I fear we have to be a bit careful with the wording here.
Definitions:
A SLIDE is mainly designed for use in the evacuation of an aircraft on 'terra firma'. Typically found on Short/Medium-Range aircraft as the A320.
A SLIDE-RAFT is a bigger version of a slide (typically 2-lane) which features additional survival-equipment (water, foot, roof, rows, pressure re-regulation, manual inflation) an ist meant to carry 30-50 of peole for longer periods of time.
Slides and Slide-Rafts are Self-Inflating if doors are opened in 'Flight Mode' (sometimes called 'Automatic Mode') and can be detached from the airframe after inflation.
A RAFT is a portable, self-inflating version of the Slide-Raft (less the slide funtionality) and has to be manually brought into the water after a ditching.
In my airline the A320 does only carry SLIDES, even when operating over extendes water areas. No rafts are required by certification authorities. Obviously a slide can support a couple of PAX for a limited amount of time (limited as there is no way to re-regulate the slide pressure).
Our Intercontinental Jets like A330, A340, B744 feature SLIDE-RAFTS and portable RAFTS with a total capacity way in excess of the passenger capacity of the aircraft.
The Slides of the accident aircraft definitely look like our slides, not sure if AI offers SLIDE-RAFTS on the A320 as an option after all.
The A320-Overwing-Exits features a more complex, two-lane slide 'around-the-corner-down-the-wing' to get people quickly down the wing in an evac-scenario. I doubt that it will be of much use in a ditching.
Regards, MAX