Are there any drivetrain components designed and sold to last longer? If a chain is only supposed to last 2000 miles, a rear cassette 5000 miles and a chainset only 10000 miles, then, at a modest 100 miles a week you are going to go through 2.5 chains a year, a new sprocket set every year and a new chainset every couple of years.

Doing this near-constant refurbishment properly (and paying workshop rates) will mean paying for the bike twice-over in the first two years (or thereabouts).

I have seen components advertised as lighter/stronger/funkier, but, as of yet, none have caught my eye due to their extended 'service life'. Are there any parts sold with 'service life' part of the USP?

If not, why doesn't anyone want extended service life? Do none of us look past the thrill of having a new bike and look for something that will last?
This doesn't help with the longevity of parts, but if you are doing 100 miles per week, you may want to learn to work on the bike yourself, and invest in your own tools.  Let's face it, at 100 miles per week, you'll probably be working on the bike at least a couple times a month (bearings, brake adjustments, flat repairs, etc).  So why not add in the tools to do your own drive train, and lower the cost down to parts alone?

For your drive train, you would need a good set of hex wrenches ($19.95), a chain breaker ($15.95), a cassette tool ($5.99), a chain whip ($21.95), and a crank puller ($13.95).  After tax, this would come out to ~$78 (according to JensonUSA.com), but would give you everything except parts you need to do the work.  I have a hard time imagining that this wouldn't pay for itself within the first year of regular maintenance.

I would also invest in a chain cleaner, as they can increase chain life depending on your usage.