I don't think a person should not have children because they don't have enough bedrooms, but when they get here, please please please try to flexible about what they need. One or some of them might need privacy. When / if this happens please consider:
partitioning rooms;
Creating private play / study space for individuals (converting a shed; "rights" to certain shared rooms at certain times; finding spaces in attics or under stairs for a desk-chair; curtains around beds 4 poster style; whatever you can think of)
I shared with my incredibly dominant sister while my dad had a study (as well as my parents sharing a bedroom) and my baby brother had a room to himself with a double bed. (the study was a box room that barely contained a desk and I would have killed to have it as a bedroom.) I know why my dad needed a study for his work at the time, but when I was struggling with my sister and there was no flexibility at all for me, it really hurt.
I was not allowed to have a lamp on to read (used to sit on the freezing landing with a book until shouted into bed - my sister used to need the light off at 8.30 pm at the age of 11). I was not allowed to have silence (radio on, prattle activated as soon as she appeared to beam her monologue at me) I was not allowed the window open (radiator up to max and full fug). I was not allowed my own socks and pants (I used to try to hoard my good ones and she would take them when she felt like it, when her own had stained soles or gone grey). I was not allowed the top three drawers of the 6 drawer chest but had to grovel in the bottom ones (even though she went in there whenever she wanted the socks that I had kept in good shape).
Every time I asked for something I was made out to be crazy and unreasonable. Looking back I do not think I was a nutter for wanting to have control over my underwear but the way I expressed it was always from such a point of desperation that I was written off and ignored.
I still struggle with many aspects of relationships and negotiation because I have basically been taught that I don't matter and my needs or preferences are not just unimportant, but actually slightly mad.
My sister is a special case and really does just dominate all spaces, all airwaves, that she is ever in. but please please please think about whether this is happening to your future children and be clever about how they each get what they need even if one of them is like my sister.