Resuming the whole thing: you can't have more than 1 or 2Mb of chip RAM plus 9.5Mb of FAST RAM on plain 68000 CPU.
1 or 2Mb pending the Agnus/Alice version (Alice always accept 2Mb), then up to 8Mb of FAST RAM on "normal" way (Zorro-2 autoconfig space) plus up to 1.5Mb using the slow-RAM space.
Using a full 68020 or better CPU is another huge matter, as they can handle up to 4Gb of address "space". Not the scope of this thread.
BTW: Alice is also beyond this thread's scope, as it is the AGA Agnus equivalent.
Comparing it to the available pc equivalent of the era: the 8086 CPU only can handle 1Mb of RAM, at the same time the 68000 can handle 16Mb, which, in Amiga terms, means up to 11.5Mb RAM. Not bad! Not bad at all!