Yes, it is technically "possible", but that isn't the same thing as being able to work for that family. For instance, I likely wouldn't pull 8pm fps at 11am, because we would have to leave the park before then to get my daughter to bed for the night. Families with young kids don't always get to stay in the parks that late. I don't know if that is the case for that poster personally, but I wouldn't respond to someone's saying they now have to get there at rope drop and tell them that fps are available day of.like they always have been either. Fp+ has changed distribution and its quite likely that it will cause those who are not eligible for fp+ right now to change their touring style to accommodate it.
I'm the poster she was responding to and no, I too wouldn't pull a FP for that late. Again we are usually only in the parks until around lunch. I normally work night shift and the evenings is when I normally sleep, so even on vacation I am usually in bed early. Making rope drop is easy, since I'm always up in the early hours anyway. Making an 8:00pm fast pass isn't happening.

That was one of the reasons I wasn't happy during my Sept trip. I got to DS at rope drop, rushed to TSM to get a fast pass and still got a return time of like 2:00pm. I have never gotten a return time that late, when I arrived right at park opening. FP+ people had already gotten the early slots and we got what was left over. I never stay in DS until 2:00pm. I normally make rope drop, grab a TSM FP that has like a midmorning return time, then ride it twice standby, run over to Star Tours, then do RnR single rider, then it's time to use the TSM FP. Instead in Sept I got a FP with a 2:00pm return time, then got in the standby line where I waited 55 minutes. Yes, 55 minutes shortly after rope drop. When we finally got to the part of the queue that's right past the log cabin, where the FP people join the line, we saw why the standby line was soooo slow. People with FP+ were having trouble getting their MB's to work. Heck, half of them couldn't even figure out that they had to line the Mickey heads on the bands up with the Mickey head on the scanner.

People keep saying it's not going to be that bad, even if you are staying offsite. Well, I experienced it when I was there in Sept and FP+ definitely made my waits longer in both the standby lines and the FP lines and I got to do alot less (ride fewer rides) than I normally do on my trips. Sept is usually slower than May, but we got alot more done and rode more rides in May with shorter waits, than I did on my solo trip in Sept.