There's a chance when Cliff puts the new flash space to use it could be for a new feature instead of just expanding existing spaces.
Someone suggested some Amp Profiling based on some patents that have become public. Someone else said maybe adding custom Amp Impedance Curves. Maybe something else could be added that needs some new storage space.
If anything like this is added, only the Mark II will be able to support it. But we don't know what it will be or when it might be added, so it's up to you how worried you are about having access to this when it comes, vs just waiting until the feature is added then deciding to upgrade then.
But I'm told the Axe FX II kept the same core models and features up to date for all versions through it's life, and additional features that needed extra space like those were only enabled on the newer versions. So if you don't think you'll need whatever gets added your III should stay up to date and useful.
The Chip itself isn't more powerful from what they're saying and the firmware itself isn't any larger to fit more things, so we shouldn't miss out on too much.
...An RGB screen, ...so .. ... PacMan :0? 
..just saw somebody play Doom on a pregnancy test window (which is somewhat fitting), so I’m SURE we can shoe-horn PacMan and/or Pong onto this thing, ...for between sets!
