The biggest threat to Instagram is distraction from apps like Vine.
While some people will choose to capture the moment using both apps, most people will choose to use only one.
Right now, Instagram is top of mind. Vine still has a long ways to go in building its community and getting people excited about telling stories in video snippets.
There are other challenges too: Smartphone video quality is still rough, particularly the sound, and Vine could improve the speed and workability of its app. Uploads take some time and often fail.
I’d be shocked of Instagram isn’t working on its own version of Vine. Recording still imagery and video should be merged into one app. And video filters are inevitable.
Images are powerful, intuitive stories. Video gives images further context. The mediums are complimentary but we’ll often have to choose one over the other or we’ll miss the moment.