Help- how long is too long to store quail eggs?

First of all, hello- I'm a lurker, recently become member, and will post an actual intro post later.
Most importantly, I have a problem. I bought some coturnix quail eggs locally and took them over to my neighbor, who said he'd put them in his cabinet incubator. That was about 15 days ago, and they had been laid that day. This morning I found out he totally forgot and they've been sitting on top his cabinet ever since.
My question is- is it still worth bothering to incubate them? Will some of them hatch? I've never tried to hatch eggs after longer than about a week of storage. Any expertise would be appreciated.