The problem is that these companies can remain on life support for decades, phoning it in and making things continuously worse as their desperation grows.

If they follow the path of IBM and Broadcom, they will move away from the consumer market and focus more on the enterprise. If Google fully realized that vision it would be extremely disruptive. Them shutting down Google Reader practically killed RSS for quite a while. Imagine that level of disruption with products that have mainstream appeal… mail, maps, docs, search, etc. It would be pandemonium.