I think any serious competitor is going to have a hard time since Blackboard has been known to sue on their ridiculous patents... their legal history is sickening...
From getting to know the guys at Instructure over the years I'm sure they have considered everything that might be coming down the pipe. If anybody can navigate the waters and succeed competing with Blackboard, it's them.
http://en.wikipedia.org/wiki/Blackboard_Inc.
and
http://www.downes.ca/blackboard_patent.htm