This is what i suggested for 5E to some folks (not quoting names). Have a common base then branch out the systems (including character advancement, combat, situation handling, magic points) into the following branches:
(a) boardgame/MMO gameplay (4E rules actually really suit boardgaming as i mentioned in several other postings)
(b) basic rpg (for those who wants freer rein n quick take-up. Good for introducing new players n novice or simply just like basic or 1e style)
(c) advance rpg (enuf said. The power rpgers. Weapon skills, encumbrance, dual, power feats, gongfu, etc. Yet it must be similarly modular like 2e)
(d) mass scale combat (something like runewars or old d&d battle system)
(e) progression variants as add on fluffs (running a realm like soccer manager, immortals)
A few examples of common base framework(i wrote more than what i am saying here):
(1) the theme, realm, npc characters, history, etc
(2) races
(3) classes (which should be dictated by the theme)
(4) points (or whatever u want to call it) system to influence (a) - (e)
(5) base combat (eg. initiative, decide action, hit, damage, react)
(6) base character advancement
With that, wotc can still keep 4E players happy (play (a) and buy (a) materials), old school rpgers like me can play or buy (b), (c) or (e) (although i like the old battle system too :p)
Wargamers will go for (d)
People who has the purchasing power or like to be complete can buy all! :)
How is it doable? Definitely. I had given some case scenarios but they will have to hire me to take it further. Let's see if they consider it :)
