HTC has sent out the latest 'save the date' reminder. This one is set for Tuesday March 25, 2014. As often happens, HTC hasn't offer much in the way of specifics here, and has simply offered a date and time, along with a location. Basically, nothing in terms of what they are planning to show during the event.
Of course, speculation suggests we will be seeing the successor to the HTC One. The handset is currently still using the codename of HTC M8, and has also been referred to as the One 2, One+ and One Plus. Though, based an earlier trademark filing from OnePlus, there may be a valid reason for HTC to avoid those latter two names.
Either way though, the leaks and rumors have been increasing in frequency and that will likely hold until the time of the announcement. Along with HTC announcing the successor to the One, Samsung is also planning to announce their next flagship. Samsung will be announcing the Galaxy S5 at Unpacked 5 during Mobile World Congress.
This would get Samsung out first in terms of an announcement, however as we have seen in the past, device announcements often don't mean as much as device availability. Having said that, both the HTC M8 and Samsung Galaxy S5 are both shaping up to be solid offerings -- assuming the rumors and leaks prove to be accurate.