I am going to try to answer as many of your questions as I can to my knowledge.
1. Limiteds will be coming back as normal, and will be purchasable in the catalog like they used to be.
“Roblox will keep making Limited items - we’re currently working on fixes in response to issues seen earlier this year, which is why you haven’t seen new Limited items lately.” -coefficients
2. I am going to make a general and logical assumption for this one. The fees for gamepasses and clothing will most likely be the same as when we had Builders Club; No Membership = 90% goes to Roblox, With Premium = 30% goes to Roblox, for all levels.
“Premium offers many of the same great benefits you know and love from Builders Club (i.e. recurring Robux deposits into your account, discounts on Robux, and more)” -Roblox Blog
3. The Premium logo is apt to change, as any other Roblox logo has, the question is when? Roblox is gradually starting to become more modern/mature with it’s look as we have seen with previous updates. There are leaks of the Robux logo also being changed in the future (leaks may not be true), showing how Roblox is changing its theme. We also see many regular buttons being updates on the webpage daily. Most likely we won’t be receiving a new Premium logo for a while to my knowledge.
4. It is very clear that BC, TBC, and OBC will be removed from the Roblox site completely. The main reason Roblox is changing the membership is because of the name:
“We changed the name of our subscription product to Premium in order to clear up a common misconception among newcomers that Builders Club was required to build things on Roblox.” -Roblox Blog
With this update, it will be clearer that the membership is not enabling people to build, which Roblox is hoping will expand the developers on the site.
5. Most likely, there will be no need to revert this membership, as there is no reason for it not to be successful. Premium includes all the same benefits you received with Builders Club and more. The max monthly robux with Builder Club (OBC) was 1800 p/m, but not with Premium it is 2200 p/m. On top of this, all Premium members can join/create up to 100 groups, which is definitely better as some people just purchase OBC for group limits. You can also now DevEx with any level of Premium, which also encourages more developers to join the platform. To sum it up, memberships are transferring, so anyone with BC will realize this change.
Builder’s Club → Premium 450, Turbo Builder’s Club → Premium 1000, Outrageous Builder’s Club → Premium 2200). All Premium users are able to create and be in 100 groups, regardless of which level of Premium you have. You read correctly: that includes the Developer Exchange program. You don’t need Premium 2200 to participate in the Developer Exchange program; any level of Premium will work. -coefficients
6. This is definitely a possibility in the future, however, I find it unlikely. Other than Roblox trying to mature the platform with their simple, modern, white logo, there aren’t really as distinct levels of Premium as there were with BC. With BC there were distinct levels, BC, TBC, & OBC. Contrary to this, there is now only one membership: Premium. Since the only thing changing between the “levels” of Premium is amount of monthly Robux, there is no need to brand all levels differently. If you have Premium 450, you have just as much Premium as someone with Premium 2200. Coefficients refers to this idea of there being no distinct levels when he says, “…most comparable level…”. To sum that up, there probably won’t be different icons, as Roblox is inferring that Premium is one membership. Everyone will have the same logo, as we all have basically the same benefits (excluding Robux p/m).
7. To my knowledge, Roblox made it clear in their blog post that the (main) reason they changed their membership was because players thought they couldn’t build without BC. On top of this, Roblox is maturing/opening Roblox to a wider audience, and making a more mature, developer-intriguing membership was optimal.
“We changed the name of our subscription product to Premium in order to clear up a common misconception among newcomers that Builders Club was required to build things on Roblox. -Roblox Blog”
8. I don’t think Roblox knows the exact time when Premium will be global. I believe that it may take a few days. My estimate would be anywhere around/up to a week.
“We’re hoping to make it not-too-gradual! If all goes well, we expect everyone’s experience to be the same within a few days.” -coefficients
I hope this helped you out and answered most, if not all, your questions. Please keep in mind this is my logic and it may not be 100% true. All conclusions have been based off what Roblox/staff have done/said so far.