It will be years before anything will hit that point. I highly doubt 10Gbp will be accessible in residential in the next 10 years. Plus CAT6 is good for 10G upto 55 Meters. I don't think none of the runs will be over 100 feet.
Eh? I'm using it right now and have for several years.
You can get 10Gbps cards for well under $100.
In fact, 5Gbps isn't worth touching.
You want affordable, 2.5Gbps is the way to go.
The main reason for this isn't even the cost for the add-in cards, but the switch cost.
2.5Gbps switches are already down to ~$200 for an eight port switch.
There are no 5Gbps and below switches that I'm aware of, so you'd still have to go 10Gbps/multigig.