Is in-display TouchID actually possible?

So I have my disappointments in Apple's failure to incorporate TouchID into the display of the new iPhone X. Knowing Apple, they will probably be evil and stick it in next year's phone, if not the year after next.
A part of me is somewhat optimistic towards other people saying that TouchID is not coming back, Face ID is the future, and I wish that was really true!

Thinking about it a bit more, I wonder.. is TouchID built into a display even possible? Is there such research or products that have successfully done this besides what Apple is trying to accomplish?

It would bring myself (and probably other people on the forums) a bit of solace if there is some technical limitation that would never have TouchID working in reality. Just like no matter how you take and piece together two rocks, you just aren't going to make electricity from them. If the reality is like my analogy, I will order the iPhone X this year.

 

I like your line of thinking, I really really want to believe this, but if they were so invested in this, they should have gotten rid of TouchID on the 8 right?