This is a very tough industry for the long term, the vendors keep shifting gears from season to season and seem to be happy to loosen up distribution to achieve their sales goals.

The products you make a good living with one year are the bane of your existence the following year.

Mega price shifts in the middle of a big job are always fun... plasmas and projectors dropping by 30-50% in a few months was fun, especially since the margins are so tight to begin with.

This is a great hobby, even for most of the people who
consider themselves pros.

To stand the test of time, you will need a great business plan, a good accountant, and the charisma to get you foot in the door with that big builder or remodel contractor. After that, you will need good employee managing skills to keep the staff that you will spend tons of money training from lettering up their own vans and jumping ship, good technical shills (sounds like you definitely have this) to troubleshoot the day-to-day problems even though the manufacturers and reps told you that the bugs were wotked out on the latest software revision.

You will also need good business skills to keep cash flow on the positive side by managing your ordering, invoicing, and payables... Which is tough when every 3rd job takes a few extra hours of labor that you can't bill for, but still have to pay your guys for.

All that said, that is the upside...
It could all go south if Greenspan wants to raise interest rates any more and send the building boom to a screeching halt (we may be due, think early 80's and early 90's)....