This is something I have been curious on for some time considering a few things.
How well is the "one click" upgrade going to improve prior to the EoL of Joomla! 2.5?
Right now we have a very low success rate on upgrading from 2.5, there are many compatibility issues that are not resolved with just the upgrade and requires a few manual edits to finish the process most of the time (problems with JHTML is the most common I see).
Now I say "problems" but I just mean that after the update things do not work as intended, this is in no way saying that the "update" component is broken.
I have looked around but only found the following:
The first states that this coming December 2014 support for 2.5 will be dropped. The second states the roadmap for 3.x. However right now it is very difficult to upgrade out of 2.5, the bigger the site, the harder it is. I am not sure what causes some to succeed and some to not, in most cases we cannot isolate it to third party extensions directly (extension manager breaks and such from missing tables, and the extension manager is where you fix that).
This is where the true issue comes in with upgrading, if the site uses a massive database with something like sobipro, k2 or content builder, or just many articles/modules then the upgrade can fail much easier. Those cannot be removed, disabled or uninstalled either (ex: 4000+ items would be lost with an uninstall, at that point might as well remake the site then upgrade).
So is there any plan for improving the one click upgrade for 2.5 to 3.x to better accommodate the EoL? (like news posts or blogs) Weird question but I feel with how many 2.5 sites there are out there that are unable to upgrade it could be very worthwhile.