Just throwing in my two cents regarding future updates/extentions of the rules:
One of the first things I expect them to add are coherent movement and unit formation, probably with the movement trays they had for War of the Ring.
Reintroducing points might be on the short term list as well, even if one statement from the FW open day supposedly was that points would not return (for the core rules).
Both these additions would allow them to expand on things that are currentzly absent from the rules: competitive play and mass battles. Both of which seem to be what a large part of the community wants, and if the actually listen to what we want, they would be dumb to not give it to us, as it would be the fastest way to truly burry the game.
Especially regarding mass battles, this solves one of the biggest problems I found with Warhammer Fantasy in the past: The typical army size was so big, that starting with the game (or a new army) was a big investment financially, and lots of potential players probably shyed away from that. While that’s gone for now, I expect it to make a return rather fast, but it will be optional (and probably not be the main focus of games in the GW stores).

I actually don’t see them replacing the whole range, especially the new models introduced by the End Times and even the last two to three years before, but I expect some repackaging. We haven’t seen much about what the new world looks like, and I woulden’t be surprised if it would turn out to be rather similar to the old one.
Taking the Orks as an example, there was some talk that they are servants of the (still present) old ones along with the Lizardmen.
While the structure of the GW shop and the tags on the Ork rules don’t indicate that, it would actually fit the 40k background they’ve had for a long time, so I’ll just assume that there’s some thruth in that.
Starting from this, I can see a range of more civilized, organized Orks fighting on the side of Order. I’d expect them to be less crude and bulky, both in their basic appearence and their Wargear. Now let’s see what happens when some Orks decide to follow a newly arrived god named Grimgor, that infuses his followers with all the orkiness the old Orks had, and we return to where we stand right now, but with an additional faction of ‘good’ Orks perhaps with a touch of High Elves and Lizardmen in appearence and Wargear.
If they haven’t planned on a development like this, the same as above applies. They’d be dumb to not listen to the community, and I woulden’t be surprised if lots of people thought of a plot (for the lack of a better word) that goes in that general direction.

Moving on, we have the ranges of the Empire and Bretonia, which are as generic a civilisation as it can get. I don’t see them expanding on any of them too much, but if thje community is loud enough, I can see them keeping the models and giving them proper rules for as long as possible.

My personal favourite armies are Lizardmen and Khemri, both of which have visual styles that are greatly inspired by ancient civilisations. In the existing fluff on the old Warhammer world, the Mayincatec style of the Lizardmen was established as that of the Old ones, and I don’t see any reason to change that in general, so I assume this army is rather save from great general changes.
Khemri was the birthplace of Nagash in the old setting, and I expect him to show up in some form again. And while we’re at it, why not give at least one undead faction the style of their supreme ruler and save my second army (and perhaps even give them the core skeleton wariors they deserve since two editions).

This might as well be wishfull thinking, but if I’m not alone in this and IF GW actually starts listening to what the community wants (which they should if they don’t want their game to die a miserable death only to be forgotten by former fans that moved on) I think at least some of these hopes might come true.