I know plenty of people ( mostly because of my role within the ABA) who have breastfed children up to the age of 4 ( ithink was the oldest)

I will happily breastfeed with out trying to wean probably up till 2 yrs then try and gently encourage weaning. But I believe that baby lead weaning is the best and easiest way. I could get to 2 yrs and be happy to continue.
I would tandem feed, I would feed twins/triplets, in fact i would try my hardest to breastfeed how ever many babies I happend to have in one go. I think I would feel to guilty to say no I'm not breastfeeding these babies just becasue there was 2 or 3 or 4 or more at once because if I had them one at a time I would breastfeed.

I am a HUGE breastfeeding advocate (in case no one noticed) so my thoughts aren't would you breastfeed but why wouldn't you??