Just that really.
Do you expect that with the housing market as it is that they will just stay at home for a significant amount of time? Is this something you are happy with?
Would there be a cut off point or age you would ask them to move out if they where still at home and they could afford to rent and obviously had not found a partner or had a family?
I love my children dearly but the transition from teens to adults has been challenging with one of them and I cannot imagine being 60 and wanting some space and peace to relax and still living with them!