You appear to be correct on CURRENT membership, based on the conference web sites.
I think some of these schools have announced that they are moving on, however.
MCC - I have Clarke heading toward D-III, and eyeing the IIAC, which would take the MCC to 8 upon their departure.
GPAC - their web site shows 13 schools.
Sioux Falls was just approved to go to D-II (they and Minot St. will be applying to the NSIC)
Concordia, Doane, Hastings, and Nebraska Wesleyan are all headed to D-III (I think, I have no info on future conference affiliation yet). If I am correct, the GPAC would be down to 8 after they transition.
Those 4 are all in Nebraska. This has the other Nebraska schools in NAIA at least contemplating their future competiton level. At some point, Dana (GPAC), Bellevue, Peru St. and Saint Mary (MCAC) have all made rumbings about applying to the Iowa-based MCC. (were 3 of those the ones that you said were recently rejected by the MCC ?)
Midland Lutheran (GPAC) has thought about exploring NCAA D-III, and York (MCAC) has looked into the GPAC.
The NAIA schools seem to be a bit like rats on a ship that is slowly sinking.
In addition to the GSAC that you mentioned, the other California NAIA conference (the CPAC) has also discussed moving as a whole up to NCAA D-III. I think this last happened a few years ago with the UMAC (Upper Midwest - mostly Minnesota schools). About half of the mostly-Ohio AMC applied to move this past summer (only 2 of 6 were accepted by the NCAA). The other will likely re-apply and when enough Ohio independents show up in D-III, they may congeal into a conferenece. This flight out of NAIA seems to continue unabated, and the process would be much less traumatic if conferences moved as a whole.