Of course it is surprising and it's a move that exposes them to a difficult situation until the product is launched.
Trying to keep selling a console already struggling after announcing that your next gen console is out next year is not easy.
And we're already seeing the confusing message ( exclusives/not exclusives, same games in 4K/developers can do whatever they want).
I think they thought that considering the XB1 situation it was worth it to try to build hype for the next product early but without having games or things to make people excited about besides a few key specs, it's not going to be easy.
Imo it was a wrong choice, I dind't expect them to announce the Scorpio this year. They could have waited for January or February.
MS took the risk so future Neo buyers might change their minds and wait for Scorpio.
A very risky strategy considering that people are focused on ''here and now'' and they'll soon seen actual Neo games running on the console (with Sony preparing contents to highlight the differences), while Microsoft won't have anything to show until next next year.