Mattel Electronics created a working specification for the "MAGIC" chip platform in 1982 with a 240×192 screen resolution with hardware scrolling with 4-color sprites, a 68000 CPU, advanced IO (including built in modem) and DSP. point-of-view two-person tank battle played over phone lines was talked about as a typical Intellivision IV application. This would have been a radically new machine (unlike the planned Intellivision III which would have been an ultimate combination of hardware that existed at the time). Dave Chandler’s team communicated with Phillips at the time regarding manufacture, and dedicated engineers were added to work on the "machine for the next decade". The planned release was 1985. No known hardware mockups exist, and prototype graphic screens or audio artifacts are not known to exist today.
If the system was released when planned, it would have clearly been more sophisticated than everything else on the market, as the NES was barely in North America at the time, and equivalent games would have been only available on something like the Amiga.
Source Links:
media0101.intvprime.com/ba4ef/intellivision-echo/References-Unsorted/papaintellivision.com/pdfs-searchable/CCF10272011_00005.pdf
web.archive.org/web/20200109173049/www.thelogbook.com/selectgame/2018/10/21/303-odyssey3/
history.blueskyrangers.com/hardware/intellivision4.html
archive.org/details/19830325NorthAmericanPhilipsMeetings/page/n25/mode/2up