Originally posted by Pål Jensen K2 already exist...
But it's not a digital camera! Mmm... I'd make several branches from zero (from smaller to bigger), using Q for the Q mount, and K for the K mount cameras, M(edium), F(ull frame), A(PS-C), and 43 (micro four-thirds if interesting) sizes. This would mean a clear, simple and predictable way of naming things: KA-1 would be the DSLR successor of the K-3ii, and MKA-1 the mirroless equivalent, KAP-1 the successor to the KP if interesting, and KAS-1 the successor to the K-70, which is really important to keep the foot in the entry level market.
To summarize:
DSLR:
K-645N > KZ-645 >
KM-1 (medium format) >
MK-2, etc...
K-1 > K-1 ii >
KF-1 (all full frame are of "pro level") >
KF-2, etc...
K-3 > K-3 ii >
KA-1 ("pro"/"prosumer" level APS-C cameras) >
KA-2, etc...
KP ............ >
KAP-1 (compact, light, compromise APSC cameras; advanced amateur/prosumer level) >
KAP-2, etc...
K-50 > K-70 >
KAS-1 (simpler cameras for entry level, amateur photography) >
KAS-2, etc...
Mirrorless:
MKM-1 (mirrorless, medium format camera), etc.
MKF-1 (mirrorless, 35mm format camera), etc.
MKA-1 (mirrorless, APS-C format camera), etc.
Q > Q-51 > Q-10s >
Q100, etc.
Easy peasy :-)