In two decades' time, an iPhone will appear just as quaint as a first generation iPod does today. Who remembers what amount of RAM those had?
VR and AR will probably rule the day, with apps opening up as parts of your visual field, the amounts of ram and processing power will be vastly different from what we know now (e.g. 64 MB of ram was considered a good amount back in 2001, that amount of ram is not even a drop in the ocean now, let alone the almost unimaginable difference in ram speed).