There'd have not been need of a survey for these simple reasons:
Warhammer existed and had the best fluff and artists.
Annual manuals with FAQ and rules revision ( Warhammer Chronicles) and selection of WD articles.
Free downloadable rules for skirmishes and smaller games on GW site( Skirmish, Path to Glory, Warhammer Warbands) plus wallpapers,tutorials for painting, converting and sceneries and much more material on the old Gw site.
Listening to community when they did Dark elves errata (dark elves forum sent a letter to GW) plus answering mails in WDs.
Campaign books plus General's Compendium plus paper catalogues.
Proper Games Days with previews and Golden Demons held in different countries.
Eeeeew all that sucked! 
I don't think they'll ever go back to Warhammer as it was. While as enjoyable as it was, the world itself made Lizardmen fighting Empire a stretch unless it took place in the Empire, and there's not much room left in the World that Was to create any new kind faction. It had become stagnant.
This is a common sentiment among people who appreciate AoS, and it's nonsense on toast.
We'll deal with the second point first and then go back to the first: no room for new factions? If they ransacked the history, myths, and folklore of the Middle East and Asia in the same way they did to Europe's, they could double the number of factions without breaking a sweat, and many of them would be just as outlandish and fantastical as what we've seen from AoS. Hell they hadn't even finished mining European stuff - Tilea and Estalia were little more than names and some broad archetypes, the Border Princes were rarely explored and never in any detail, even Norsca could have stood fleshing out more. So aye, without even going outside the Old World - Estalian Tercios, Tilean Condottieri, revamped Fimir, and a more explicitly-themed Norscan subfaction for Chaos. Araby and the Southlands could get you half a dozen more. Then you start along the Silk Road and don't stop until you hit Nippon, tapping some of the richest cultures on earth for ideas, you'd be at it for decades. EDIT: And that's just "present day" - you could get another decade or two's worth of releases by going back and covering War of Vengeance/ancient Nehekara-era, the
proper age of Sigmar ie Warhammer Dark Ages, the not-Crusades and so on, and again that's just the existing history for the existing Old World factions, throw the southern and eastern lands and cultures into the mix and you again potentially double or more the amount of material.
As to the first problem - that was a problem of GW's own making, to the extent it actually exists at all(your chosen example isn't really an obstacle at all - the various New World colonies may not have lasted very long individually other than Skeggi, but there were a lot of them spread out over the centuries). They're the ones who insisted on focusing every narrative, every army book on the biggest, most world-shattering, most AWESUM *guitar solo* scale conflicts because they wanted to sell miniatures and simply couldn't grasp the idea that making people
want to buy lots of your models is a better tactic than trying to
force them to buy lots of your models by focusing exclusively on clash of civilisations catastrofiction with army sizes to match. Yeah, it's hard to come up with plausible reasons for huge armies from opposite sides of the world to clash constantly - so don't try. Focus on the kind of conflicts that the type of setting can support; when you target your narratives down to more everyday heroes and their reasonably-sized skirmish warbands of say 30-70ish models it's much easier to plausibly have them end up all over the place, because they would be. Raiding, tomb robbing, slaving, artifact hunting, seeking revenge or looking for new trade opportunities, a world like Warhammer's should be teeming with modest wandering warbands from every race constantly coming into conflict with "the locals" and each other. And don't try claiming you can't tell "epic" stories at that scale, because I read plenty of them in Black Library novels. The "minifactions" approach would work just as well for WHF as for AoS, with a little thought, and makes perfect sense at the more modest end of the army size scale.
They could quite easily have reworked WHFB along the broad lines of the LotR game, ie an AoS-style "skirmish" game as the baseline, with a streamlined rank & flank expansion for depicting larger conflicts if players wanted to.
The real reason for the switch, of course, has nothing to do with the Warhammer World being "stagnant", or lacking in opportunities to expand - GW want to write about Fantasy Horus battling Fantasy Emperor with their legions of goodie and baddie Fantasy Marines, and on the odd occasion when they deign to throw some support to non-Fantasy Marine style factions they don't want to have to be constrained by their own previous material in order to maintain internal consistency, so they simply wrote a setting that doesn't require internal consistency at all.
