If you've been tracking the progress of AOSP's development and the move toward Android 4.5, you may have noticed some concerning developments: write access to /system is being limited. According to this overview from Google+ user Chainfire, this has some serious implications:

What this comes down to meaning is that write access to /system is no longer going to be available on "rooted stock" from the Android version these commits are included in.

. . . From a security standpoint, this brings more security, and is thus better. Unlike most of the other AOSP changes I've posted about lately though, this change does not just require devs to update their apps, it will also actively inconvenience root-app users.

It's not certain whether these changes will appear in Android 4.5, but according to this recent post from Homo Ludditus, it's a safe enough assumption that anything happening to AOSP tells us all we need to do about Android in general:

If AOSP 4.5 is screwed, everything Android is screwed.

Unfortunately, if things really are that bad, it won't just be a patch-worthy inconvenience for some apps, but a death sentence:

Rest in peace Titanium Backup, ROM Toolbox, Root Explorer, SD Maid, Lucky Patcher, etc. etc.

And it's hard to say what other impact such changes could have. As the Homo Ludditus post suggests, it could lead to an Android development landscape in which only apps signed by Google could be installed - in other words, Android devices might start to look a lot more like their competitors in some less-than-ideal ways.

Take a look at Chainfire's post and the Homo Ludditus post for a detailed look at the changes.