I tried doing just now. Seems like the Me tile is still in the People Hub. I'm seeing a medium-sized photo of myself as soon as I open my People Hub. Tapping on it gives me an option to post an update, check in or pin it. Pinning it shows a "Me" label, so I think this is the new version of the Me tile. You can then edit your profile photo by tapping on your photo, where you'll be prompted to choose either one of your accounts or an image from your Photo Hub.
Thanks for this clarification. I wasn't able to observe this back in WP8.0, but I hope MS would give us the option to choose to change the profile image in one or a number of the linked accounts by selecting either just a single account or all (or a number of) those accounts in future updates.