Will Microsoft ever allow Win10 users to (GUI) theme their OS's or have they said it's not possible? Default tiles really suck! Any tips?

I was just wondering 2 things: 

1). Is Microsoft ever going to allow W10 users to theme their operating systems (the GUI)? 

2). If GUI themes *can* safely be set, how might it be possible without downloading any dodgy files from questionable sources?There are plenty of videos of how to do it (on YouTube), but many require the user install many different files and to be perfectly honest, I don't trust the files or their sources one tiny, microscopic bit plus it's all just a bit too 'involved' and convoluted, ya know?So, with that in mind, does anyone here know for sure if MS will offer up a OS patch/update anytime soon that will finally allow Windows 10 users to properly and safely set cool n sexy new themes, (such as the Aero Glass theme from Win7)?