OK, sure are many changes being explained at WPC as we know more information from the Neowin website regarding Windows Threshold.
The first thing is that the Start Screen will be completely turned off for desktop users and what we saw was the Start Menu combined with the Start Screen elements on the right side. For tablet users, it will be using modern UI instead by default but we're not sure if the desktop mode will be completely removed as it is still TOUCH-UNFRIENDLY.
OK, that was before the WPC took place but according to Neowin, there are more stuffs Microsoft is planning to do such as the chage of Taskbar, the implementation of Cortana, etc. Jeez, we don't want to see a modernized looking AI like she looks like a freaking 32X Assistant or something where the body is completely textureless with no shading whatsoever. Like what is that, a cell-shaded AI with no shades whatsoever? Not to mention that Cortana is probably from the Sci-Fi FPS Halo series in which things are looking futuristic and it may be a problem for Microsoft as futuristic things surely take up tons of skills, resources and creativity.
Another thing Microsoft should fix is that for desktop users, there should be only desktop apps as modern apps are for tablet users as suited and mixing two types is like a no-no if the company wants the OS to be much better than the original Windows 8.
Well, after the WPC event, it seems that things are expected to change.