The market seems to be every non-technical family member of mine. All they need is a web browser; if these "just work" for that purpose, have good battery life and they don't have to worry about anti-virus software or other updates, then these are significantly better for their needs than what they have.
Bigger screen, keyboard, better web experience, the Chrome store to fill in the gaps of what they might miss from Windows. Sure, there are overlapping use cases but they're not the same. Chrome OS gives them what they need/want from their laptop/desktop (e.g. Facebook, web browsing, YouTube, email, pictures, occasional word processing, etc.).
But you're changing the parameters.. You said "All my family needs is a web browser". Now you're saying they need other software that the might miss from Windows (plus what they might need/want from their laptop.
Given your original parameters, my point still stands. If you're looking for a laptop "replacement" then obviously a "laptop" is going to fulfill that need.
My core argument is that what Chrome OS sets out to provide is what most people need from a laptop; a web browser and somewhere to get "apps" (Chrome webstore: Netflix, picture editing, etc.). If it can do these well, the market for these is massive; that's my point to people claiming there's no market.
You might say that a current laptop can do this and more. The "and more" part is the issue because it ends up causing the average user more trouble than it's worth; seriously, talk to them. They still have issues with anti-virus software, paranoia about getting a virus, performing updates, anxiety resulting from worrying about what might happen if they do/don't update, resolving issues that result from updates, resolving issues that result from not updating, what to do when when it runs slow, drivers, handling files, dealing with the inevitable mess their system will be in after a year or two of use, etc.
First paragraph - second paragraph + fast boot + good battery life = massive market of potential happy users. Again, I don't know if Chrome OS will succeed but the market's there waiting for something better.
When tablets browsers catch up to the desktop on those two things, I'll consider using a tablet for more than just a comic reader (all I use one for now).
