TheDuckSun is working on a C128 that fits into a C64 case. The proto type has the following features: VIC/VDC switch, 8 bit colour RAM, 6-36 VDC, Dual-SID, etc. You can follow the progress on Forum64.

Official web page for the C128 RM.
2018-04-20 - 13:17:00 - Week: 16 - Item number: 6191 - Category: C128(D), Hardware