Market size is definitely something that would need to be considered. I agree that the bread and butter would be the upper middle class, but I think you may be underestimating how large of a market that is. There are 115 million homes in the US, with 20% of them earning 100k or more [0]. Only a negligibly small percentage of those make over a million which is the lowest I think you'd have to make to justify the cost of a personal assistant. I also think you're oversimplifying the problem and making an unsafe assumption about how many people have this problem, but I could be wrong about that. It would need to be tested.

House cleaning should probably be an optional add-on, but I think you're underestimating how big of a market that is too. Approximately 10% of households seek outside help with at least some of their household cleaning chores.

[0] http://www.npr.org/blogs/money/2012/07/16/156688596/what-ame... [1] http://www.housecleaningbiz101.com/CleaningIndustryFacts.htm