The only machine you will be able to do this on is the Mac Pro.
Simply due to the fact that it has slots available for this purpose.
The USB3 will likely be part of the next generation I/O chip in Intels next mobile chipset.
These chipsets generally aren't plug and play replacements for the previouse generation and require new logic boards/motherboards.
For a PC this isn't a huge expense, for an Apple computer you are looking at $1000 minimum if Apple doesn't change part locations, wiring, heatsinks.
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Generally less expensive to sell the entire machine - eat the loss - and buy a new one.