With the additional info you provided, I would go. You are already doing a cheap trip by WDW standard (you might cut on park days to 1-2 only and plan fun by the pool like others said), you have savings in the banks, someone in the house who still has a lob and can increase to more hours if need be. I mean, this is not worse than many families with only one income, the difference is that you'll become the main provider in the house. You are not losing your only family income, which makes a big difference for me.
We had a related situation here: we are DINKs, and usually travel 2-3 times a year. A few months ago, while I wanted to book our all-inclusive beach vacation for the spring, my boyfriend was not so easy about that: his company is not going real well (proven right, they cut 7 out of 15 employees 3 weeks after that discussion), so we decided not to take that vacation. However, I really wanted our WDW trip this fall, so we had a sit-down and looked at the numbers. Our emergency fund is pretty large (enough to live 4 months with NO income at all), we live way below our means, and have little debt: a small mortgage and our one car will be payed off in 3 months. We can live on one salary no problem by cutting extras like vacation, restaurants, ... And that was not including unemployment. So we felt there was no reason to spend our saved vacation money of this pretty cheap trip. If something happens before that, I know we'll cut the rental car, days at Seaworld, ..., and will enjoy ourselves, knowing we can still pay all bills regardless.
As for the plane tickets, unless you booked with Southwest, you'll only get a credit for the ticket cost minus the change fee (up to 150$ each ticket). On Southwest, you'll get the full value as a credit, to be used within 1 year of original booking. They don't really care if you lose your job or something...
