I was asked to do this some 10 years ago with our toddler group which was under threat of closing..... after careful consideration, I decided it was up to the current parents to keep it going... and hey presto! 10 years later it's still going strong....
My concerns centred on - what if I get another child who doesn't want to go (minder) ? what if I get a job and have to leave anyway? it wouldn't be paid so what if I got resentful? would I really want to keep going on something that my children have grown out of? it's always the same people doing things - let the others learn! I want to support my children now - and I won't have time to do that and run the playgroup..... so I decided to look forward and am now a school governor!!
Hope this helps!