Totally agree man.
If I'm them, I release this - I'm talking big amps as gotta give them props as they've done well on the smaller heads. As for IR's, I really think Marshall should partner with someone. They could do a new take on their old Speaker Emulator, the original one was fantastic for it's era, now partner with someone like Two Notes and develop something specifically for Marshall. Two Notes is getting their cut and their branding out there.
Modded 800 - right out of the box enough gain and punch, no pedal needed. Plant the flag, prove the naysayers wrong. Afterall this is the mod platform.
Modded 800 - call it the 802 and add dual masters and dual gain pots. New take on a classic that many modders go ahead and do.
Modded Plexi - with all the Jose style tweeks. Same as above with the 800.
Updated JVM - call it the JVM 100 and JVM 50. Dual Masters, Dual Gates, Res, Pres controls. Channel one with three modes - ultra clean, breakup, 800. Then OD1 from the 410 with green, orange and red. Midi. No reverb. All knobs on a single row, not the stacked rows of the 410/205/210 which freaks the novice out. Serial Loop on back. I'd snap that up the day it was released.
Modded Jubilee - with built OD pedal.
MD61 - update that with knobs for Res, drop the Reverb and then drop the entire DSL line. This takes it's place.
I'd also get back with Slash and finish that amp that he was prototyping a few years that apparently everyone loved. Also got to get some other high profile players back in the fold. If that means signature models, do it.
All made in the UK as well. Lastly, work on lowering that pricing.
As for pedals, since other companies have stolen the circuit why not release a Noise Gate Pedal, priced right it would knock a dent in a few "boutique" guys pedal business. I also think I would repackage the currently lineup of pedals, same guts just smaller footprints. And I think I would do a Marshall in a Box style pedal with IR ala Friedman, Victory.
I'm just waiting to be hired lol.