co sleeping when dc2 comes along?

[livingforthemoment]

My ds has just turned 4 and has been co sleeping with us since he was a tiny baby. We would prefer to co sleep until he is ready to sleep on his own - do they usually reach this point independently (and when, on average?), or will some form of 'encouragement' be necessary if we don't want to continue this into middle childhood?
Problem is our second baby is due in a month and we want to co sleep with this one too, without ds1 feeling pushed out.
My dh will be sleeping in the spare room for a few months while I do the night feeds as he needs to get up for work, so we'll have plenty of room for a while. Ds1 has made it clear he'd rather stay in with me and the baby than join dh in the other room but i've got no idea what we'll do when the baby starts sleeping through the night if ds1 is still not ready to leave? We have a serious lack of space as it is, and can't move house but we want the baby to feel close to both of us. The only solution I can think of is if ds1 sleeps in what will be his own room with dh or myself one night, the baby in our bed with one of us, and we take turns co sleeping with each child?
Would love to hear about other people's experiences in this situation

I'm a single parent, so space isn't so much of an issue.

DS1 always slept in my bed with me, but I started trying to move him to his own room when I was pregnant with DS2. By the time DS2 was born, DS1 was sleeping in his own room for most of the night, but still coming in to my room at some point in the early hours.

I must admit, at first it was very tricky because it's hard to keep a newborn safe (no covers etc) while there's a hulking 4 year old jumping about too! But after a few months it got easier.

Now I have DS2 in a cot pushed up to my bed (with one of its sides removed to I can still feed DS2 at night). DS1 sleeps on the other side of me.

The hardest part is when one of them wakes up and the other is still sleeping. Keeping a baby quiet is impossible, and keeping a 4 year old quiet isn't easy either. And of course, if I dare move, they both wake up!