According to a report coming from TechCrunch.com, Xiaomi might not be attending MWC 2017 at all, which could explain why Hugo Barra decided to jump the ship just before such a big event.
If you remember, Xiaomi used last year's Mobile World Congress to announce its Mi 5 flagship and with earlier rumors about the Mi 6 and the Mi MIX EVO, everyone simply assumed that the company will be at the show.
This also does not mean that the company won't announce its newest flagship during the show, just that it won't do it in Barcelona, Spain. This could also mean that the company might go the way of Samsung and announce its phones at a separate event but if it decides to announce the new smartphone, it could draw a lot of attention from big players at the show.
In any case, the show is just over a month away and we will probably hear more from Xiaomi as even without Hugo Barra, the company still has a big impact on the market.