Kobo need not worry about Apple getting into eink.
Apple already has the reading device they want: it's the iPad mini.
If Amazon doesn't believe eink is the end-all of reading devices, why would Apple?
Right now LCD is evolving way faster than eink and I'm starting to suspect LCD will match eink power use long before eink ever gets fast saturated color at a viable cost. The red flag is Amazon buying Luquavista. As eink's biggest customer, would they have done that if they saw good color eink on the horizon?
And remember, while outdoor readability is a great eink marketting point (Amazon exploits it nicely in their commercials) it really hasn't stopped zillions of folks from reading on tablets. It argues for nichedom more than a must have...