Call me a pessimist, but I think it is impossible for everyone to be in love with their job. It's a naive individualist/relationist dream from us privileged 1st world dwellers. But aside from my negativity, there's a good book by Jeremy Rifkin, which I have recommended numerous times, called The End of Work. Rifkin's theory is that there will eventually be a collapse in blue collar jobs, creating mass unemployment and turning former workers into government-supported vacationers. The specialized will still be employable, but the vast majority of blue collar and management jobs will be replaced by technology.

Different situations excite different people and I think that even if people only did worked that was engaging and fulfilling, all the work that needed to get done would. I agree that many jobs would change or be automated. And perhaps our choices would reduce (not a bad thing in some cases).

Consider the fine folks who have created a business out of picking up dog poop in New Mexico. They have a waiting list for new clients! They LOVE their business and they do it well. Others might cringe at the thought of scooping poop all day.

Would we have huge organizations? Perhaps not like we do today. I think they would be clustered into smaller groups of no more than a 200.

Interestingly, the really yucky jobs would pay extremely well, because it would be so hard to get people to do the work. That would test our will, I am sure.

I think that we can feel a sense of accomplishment and meaning, and get excited about work that others think is dreadful.

The question assumes that people know the type of work that excites them, and I bet many people have no clue about this. In this hypothetical scenario, perhaps the job in highest demand would be the one for those who help people see the work they are best suited to doing.