Intel may be doomed, but I think not. It is room for lots of actors. To use a general purpose CPU for Video and 3D and multimedia in general is by definition a terrible waste of precious battery power. I think we will see more netbooks and tablets being built as the N8; a modest cpu and a higly specialized video and 3D chip. Nevertheless, multi-core ARM wouldn't hurt power consumption too much, so Intel may very well be doomed, sort of.

The problem is that even small improvements in battery technology would be very beneficial for Intel, and battery technology will be improved.