I was chewing on the tenure idea too, Alice. On the one hand, I see the point that tenure may lead to complacency by some people. But I seldom actually see that happening in my university -- it seems like people are moving as fast as they can.
On the other hand, tenure could be seen as providing a level of protection/security that would lead to greater risk taking and personal investment. But I don't see that happening very often either.
I just don't see tenure as all that important a factor in the long run. One of the biggest culprits I see is time. Most people I know in higher education are living frantic lives, and at a pace that discourages investing in anything new -- anything that takes time or energy. Technology, teaching, public service and most anything else that is not deemed "mission critical" and rewarded by the institution are often neglected as a result.
I like your idea of encouragement, because I do think that once instructors experience the excitement and potential of technology to support some exciting learning opportunities for students, they will be "hooked" on the experience and the satisfaction.