I strongly believe that the work will drop, because less people will be needed, and the expected quality will be higher, because manual labor is expensive, but it will remain. Like in car manufacturing. You buy a car and pay for it, but there are expensive hand-made cars that you can buy, and they are highly customized, with personal attitude toward the clients. Manual software implementation can go the same direction as hand-made cars.
So I agree - the number of professional software engineers may decrease, but it isn't going away. And based on what I'm seeing in my consulting gigs, the senior folks won't ever be replaced - they may spend more time fixing slop than doing greenfield work, but the jobs will be there.