The Pentium M is indeed a worthwhile chip to look at, but there is still a number of flaws with it and as far as I can see it Intel needs to release an entirely new line of processors to properly compete with the Athlon 64s.
First, the fact that the chip requires an additional piece of hardware to properly work in a socket seems a bit of a hassle in my opinion, and overall hinders the fuctionality and possible overclockability of the ship. The average PC user is not going to go through that sort of trouble to get a working platform.
Second, the lower power consumption of the Pentium M is nothing to brag about. AMD desktop platform cores have overall low heat dissipation, and AMD Turion 64 will be offering 35w and 25w core solutions shortly. Furthermore, Socket S1 has planned >7w ultra low power Turion processors.
Third, AMD is simply dirt cheap right now. DDR2 is the real thing that's hurting Intel at the moment and is keeping a lot of us enthusiat crowd away from it now. Fact of the matter is you can buy a $200 3200+ and achieve the same performance of an $800 XE for a couple of hundred bucks less.
I'm overall happy to see Intel starting to look beyond clock speeds and coming up with some innovative ideas, but with AMD so ahead of them now in true 64 bit processing, multithreaded cores, heat dissipation, cost, hypertransport, all which seem to improve
monthly, Intel needs an AMD flop at the same time they come out with a miracle to gain back the enthusiat market.
All this being said Intel is still the king of the playground and most people are still gonna stick with a genuine Intel just because to the computer illiterate eye AMD looks like a poor solution with lower clock speeds, smaller cache sizes, slower FSBs, and "outdated" DDR1.
Single core processor days are not numbered. Not that this is any laibility to AMD, since they have a great number of outstanding dual core processors. Its all about the type of application your processing. Dual cores in certain areas perform worse then a single core, vice versa. The field is equally open.
Single core processors have reached a thermal wall which multicore processors can surpass. Although there are few multithreaded applications around now, that's nothing but understandable since there is no platform to run them effectively on. Software will migrate to multithreaded processes and multicore processors will thrive, obliterating the single core entirely.