I... no. Aside from the inappropriate ask of having them all give up their current lines of development and design and start new, that doesn't yield a gaming community that I want to see.
Despite my purple prose, what I'm envisioning is not far removed from what Morrus and others are talking about in regard to renaming any SRD names and terminology for a re-released Level Up. And how Paizo is saying that "Pathfinder will continue." At its simplest, 7E would just be a coordination of that new non-SRD terminology across an alliance of several companies. That will require a bit of retooling of development and design, but not much.
But at another level, 7E would be something like the
3.5E Hypertext SRD. Consider how, with the UA Variant Rules, the 3.5E SRD is really several different RPGs! It's just presented as a single game: 3.5E.
7E would be like that.
Okay, I admit that it'd be easier if only the 5E-based games (e.g. Level Up) were included in 7E. But still feasible if the D&Dish 6 ability score games were included (PF, OSE, C&C, etc).
If you lined up each mechanical feature of Level Up, PF2, PF1, 13A, 13A2, C&C, OSE, and every other significant D&D-ish / 6-ability score RPG whose name escapes me at the moment, we'd find that really there are a lot of similarities.
Those would all just be variants of the core 7E system.
There'd even be an array of modular variants which would closely model each previous edition of D&D. But it'd all be part of 7E.
Something like how Paizo designed PF1 and PF2 with the intention of taking D&D up a notch, but this time with several design studios working in coordination. And with the resulting game containing so many modular variants, that it can essentially model any of their previous D&D-esque rulesets.
It's true that certain features of the core system would be changed in the course of hammering out 7E together. There'd be some streamlining and improvements. Some terminology would be unified. But these would be features which this all-star alliance of game design companies decide are good for the game. So it's not just a 'genericizing'. It's a new shared edition.
I'm a licensed "pony wisher", so I'll add one more feature which would enable 7E to hammer D$D5.1....
...by hiring a massive team of rules-converters, the entire content of the 3.5 SRD,
d20PFSRD and
PF2d20SRD (massive!!!), and 5E SRD (with serial numbers filed off, of course) would be included in the 7E SRD from the start. Twenty years worth of Open Game Content, already converted and ready for your table. 7E would be the first edition to skip the trickling rehash.
This is the problem. That's kind of like saying you have one meta-instrument that both flutists and guitarists can play.
Good point. Powerful imagery.
Still, if you bump up the metaphor to the level of the orchestra -- the 7th Era Orchestra, crafted by an alliance of independent RPG studios -- then the similarity is that, like 7E, an orchestra is modular. Its sections and instrumentation can be reconfigured.
It can be done... if you are willing to give up the distinctiveness of individual systems that don't operate on the same core assumptions.
Okay, I agree it'd be easier if only the 5E-based (or at leas d20+6 abilities) systems were included in 7E.
Multitools have their place in the world, sure. But every tool on your Leatherman has design constraints to allow it to coexist with other elements of the multitool. That is a major restriction, and generally means that nothing on the multitool will be better than a well-designed version of the thing that doesn't have to cohabitate.
Good point. Powerful imagery.
Still, Peter Atkinson dreamed of the Envoy system for a reason.