thunderbold is proprietary hardware which is owned by the proprietor, means Apple and intel (intel owns the name and apple the rights or so to my knowledgeor was it the other way round ) , it was developed by intel with large contributions from Apple anyway .
only Apple is using it , so any manufacturer who want to build a device for thunderbold has to pay Apple and intel some money to be allowed to use that port in a device
thats the downside if you got a port that is only fitted in computers of one manufacturer..less competition
and even a simple cable that connects 2 thunderbold ports includes circuitry inside the connectors which makes it expensive
i think Apple is charging $50 or something like that for the 2 meter cable
its like in the past with Firewire , it was better then USB but pricier thats why it didn't replace USB
and thunderbold will have the same fate , it might be better , but it will stay pricy even if some PC manufacturer one day adds thunderbold to its pc's i guess Alienware might maybe one day , but that will be PC's in the higher price end of the market as fitting thunderbold ports to a computer will be expensive for the manufacturer , so not suitable for PC's in the lower price category