Some add-ons like Y.A.V.N.E and Precise Align are critical to my workflow, and both of them add some very nice panels in the Tool Shelf.
This shelf is now (by default) gone in Blender 2.8 and neither of the above mentioned add-ons are likely to be updated since they are several years old.
How backwards compatible is 2.8 in this regard? Will I be able to start using it when the beta is released, or am I doomed to be stuck in 2.7 until someone develops equivalent add-ons for 2.8?
There was many under the hood changes in Blender 2.8 and there is no backward compatibility with adons. Some requier more, some less work, but you cannot use them just like that in 2.8.
Removing the (T)oolbar seems an absolutely crazy decision to me.
Why did they do it? So many addons rely on it, and it was just plain useful.
The silly huge buttons for scale, transform, etc. are just useless for anyone who has used Blender for more than 5 minutes.
they need upgrades from their devs or someone else, the Toolbar can have addons added to it with even their own custom widgets, also in the properties panel there is the Tool tab for all of this… and u can filter loading addons based on your workspace…and the big news addon devs can make their own custom editors. 
Custom editors are already implemented?
i think it will come around the beta once the python API is finalized, i haven’t checked the code yet ,because i only found out about it today from their talks.
I would love to see what that entails if or when that is a thing. My interest is tingling!
People are getting in such a fuss, but give the devs time to get comfortable with 2.8 and for it to settle, you will get your addons
Why not just make all the addons compatible? Removing the (T)ooltab just ruins a lot of them for absolutely no good reason. It’s very unlikely that authors of 5+ years old addons will come back to fix them all for 2.8.
Why not just you do it for all of us? Seriously people say that as if doing such things was nothing more than the flip of a switch, after all if it is that easy anyone can do it, so why not you?
The tool shelf is not really gone. If your add-on defines a new tab, the T-panel will have tabs. Only when there are no other tabs but the Tools tab, the single tab is hidden.
Other changes make it more difficult to maintain an addon for both B2.7 and B2.8, e.g. matrix multiplication is now done with @ instead of * (apparently for numpy compatibility), and operator properties are annotations (defined with : rather than =).
It’s not really about making something, but choosing not to remove it.
If what ThomasL says is true, then I guess there’s no issue, though. I just think it would be an absolutely insane idea to remove the (T)ools when so many addons rely on them.
The API changed so even if the toolbar was there most add-ons would still require updates.
About YAVNE. Now there is the weighted normals modifier with face influence built in Blender, so the add-on might not be necessary anymore.
People just need to keep in mind that 2.8 is a wip, think of it as that stage where you have your rough draft of a paper and you are now stripping out the stupid and putting it together in such a way that it flows.
I did not know that, so that is good information, thank you!
Precise align is still super essential to me, though, but I see that there might be more align options in this add-on, where the author still seems semi-active.
(I did actually want to add a setting to the Precise Align script, and began to look into how to do that, but also converting it to 2.8 is too big of a job for me, I think.)
I would like to have an equivalent to tool panel in a new workspace
where you could add whatever buttons controls you want
if possible
but I can see too many API changes for backward compatibility
in any case.
just look at the new way to select objects with the new collections!
not compatible at all.
happy bl