... that the most skilled / representative developers & designers came together to design & create the definitive modern MSX retro computer with little to no compromises.
With of course special love for audio circuitry, hw-level possibility to mix/balance chips, high quality DAC and/or digital out. Leaving video out in the middle (though it could e.g. have analog out, and for digital out/upscaling one could e.g. use the OSSC.)
Of course fully backwards compatible.
It would feel like '8 to 16 bit', be much fun to develop for, and attract loads of developers 
Pretty much a fully specced (originally envisioned) MSX3 (maybe just a little bit beefier) with additional interfacing for the modern age.
Perhaps flaws / shortcomings / much desired features of the familiar chips (like e.g. Grauw mentioned) could be fixed/implemented somehow, so that a seasoned developer could immediately take advantage of that. A new release would then possibly have a version for legacy & new MSX. 
my old Toshiba HX-10 worked 
The one thing that's missing for MSX is a proper (one, two, three?) co-processors for memory, audio, graphics and external communication all with dma and without hogging the msx bus. The Amiga, Atari and current PC's would be nothing without them, so why not for an MSX? An expansion that doesn't need (much?) modification to the MSX and is fully mod/dev friendly and open source.
MSX2 color bus to HDMI converter, something like the hdmi converter from the Amiga (based on Denise and PI Zero). With proper scaling, filtering, optional scan line simulation etc. An ADC to convert the audio to digital to be sent along the HDMI cable fully synced.
An interactive debugger (dbg?) for MSX with a connection to the PC where you can see the (C, assembler) source code, set breakpoints, single step, step into, step out of etc through code, read out variables and registers etc. Software to setup the ide easily.
Interactive, graphical (cartridge) hardware design software where you have a typical MSX bus system build in, with drag and drop, a node editor to link together blocks of logic etc. slots, memory mappers, video, audio, communication all build in as components. Spits out a schematic, vhdl and stub c code to write drivers for newly added hardware. Simulator/emulator to prototype and test. Compatibility and design rules checker.
Google translate built into the msx, so we can play Japanese and Korean games in our own language be it English, Dutch, French, German, Spanish etc without having to learn another language 
...the 8-bit guy starting to love the MSX
Hahaha, I phisically LOL-ed at this one...
In a more serious tone, It's a pity that non-msx people from non-msx countries (the typical bunch: USA, UK, et al.) seem to be specially indiferent towards MSX, but hey, it's just they don't seem to "grasp" the whole concept behind it. Well, they never lived it, fair enough... Their demos consist of just turning some MSX-1 on and then run some silly game already published on some other platform, carefully chosen for their audience to compare both versions...
They never manage to load Space Manbow, Knightmare, F1-Spirit, SD-Snatcher, some Shalom, Aleste 2, some amazing MSX-1 modern homebrew, MSX-2 JRPG .dsk sagas... Of course, trying to do this without the original games is a challenge nowadays though, It's far beyond any MSX novice user... Or someone lends them some SD-Cartridge solution, or they will never check the MSX potential with their own eyes.
For them an MSX it's a strange ColecoVision/TI-99 computer (which they already used and recall), so they don't know they're just scratching the surface when doing "deep" reviews of "our" machine. Their typical MSX demos consist into invariably running 1983 games... Gosh...
RMC comes also to my mind... He had a properly confugured YAMAHA MSX some weeks ago (with all the MIDI stuff and keyboard and bells and whistles properly configured), and he just cluelessly stayed in front of it doing "nothing" with it.
I died from the cringe and anxiety this poor demo conveyed to many non-MSX users that might have come accross that video
As you said, I wish some proper and actual MSX user living near them could phisically help (and lead) them to create a definitive proper MSX review for their channels. Everyone would enjoy it, it might be a win-win.
More ontopic with the topic, my wish would be "I wish MSX had REALLY had a better success in the USA and/or the UK"... We all would live now inside a surreal alternative universe (You know what? Probably not !)
