I think this is not nearly as much of an issue as many people think it is. Most software hasn't been CPU bound for some time. The declining CPU performance improvements seems to be leading to more rapid advancement on the storage and memory fronts. Switching from a spinning disk to a ssd has resulted in the single largest performance improvement I've ever experienced in 20 years of computing.

Conversely, while multi-core computing doesn't deliver increased performance in the traditional way, I'd never want to work on a computer with a single processor again, no matter how fast it is. The whole system can become unresponsive from the load of a single process. Contrary to popular belief, many software applications do take advantage of concurrency, and it's not particularly hard to use concurrency to speed things up using multiple processes and messaging queues.

There is still room for plenty of improvements. I personally would rather buy a 4-core processor with more on-die cache, than an 8 or 16 core processor at this point. The major improvements I'm really looking for are faster and larger ssd drives; think equivalent to 4 256GB drives in a Raid 0 array with at least 60,000 IOPS, 1TB storage and 800MB/s read and write speeds. I also want more memory in my next workstation, say 24GB.