It’s stated that since stuff like Kai Kai and instant transmission are outside the subspace’s power, Goku would be vaguely left to “wander in between dimensions forever.” That statement is honestly very loaded, and can be interpreted a number of ways.
1. You could wander forever and be stuck interacting with dimension after dimension (space-times in this context). That could make the Macrocosm 2-A.
2. Wandering “between dimensions” could refer to how the Sugoroku space is an area between space-times, and you could wander through it forever. In other words, infinite Sugoroku space (though I think it’s stated to be earth-sized in the Chouzenshuu, so that may be contradictory).
3. If “wandering between dimensions forever” means the dimensions are spaced apart infinitely, that could make the Macrocosm Low 1-C via the 5th axis specifically being infinite.
I was honestly thinking of doing a huge upgrade using that statement, but it’s too open-ended to be accepted for any concrete scaling.