Not yet! But here some work arounds...
If your studio uses png sequences by default, it may make sense to write a short python script you run every time you would like to submit a sequence to syncsketch.
The script could run a conversion from image sequence to video, then upload that video to syncsketch in one go.
Conversion using ffmpeg (see http://www.eas.ualberta.ca/dif/?page=ffmpeg)
Uploading via API - Python API Documentation