The wiring below will make it harder to work on from below. I would stand a simple prop under the ends and it should be good for another twenty years. But I wouldn't trust it as is. You don't know what troubles others have had when it was a bathroom before.There is electricity that runs under there... you can see the two lines on the left. That's why I didnt do it while it was open..... and at the time.... I didnt have the cash to pay someone to come and do it. Long story short.... I had to fix it in a hurry for legal reasons.
I am assuming those have been that way since the house was built. It was a foreclosure and the bathroom hadn't been used as a bathroom till last year. It just had plywood over it and was used as storage