What if Outland (5x xp rates, 1x all other rates) progressed with accurately timed released content until 3.3.5? But with a delay after the Sun Well Plateu raid is released for it to be properly experienced as retail rushed 3.3.0 and then wotlk before no more than 10% of the player base had experienced the final and arguably the 2nd best raid( Ulduar in first with ICC in third). The delay would also give enough time for hype to be built for the first transition of a high populated (8000+ concurrent players online ) TBC realm into WOTLK. The two greatest expansion of all time.
But I get your point, I'd actually enjoy a progression server where you get a year of Vanilla, then TBC launches, and so on. Mimicking Blizzard's release dates would be overkill. Players are better, strategies are known, specs are stronger, etc. Most casual guilds would burn through the content.