This is the buyers problem, or his bank, but it only becomes their problem if they are somehow made aware of it.
Your obligation and your solicitors duty of care centre on your house, not the estate.
Even the architect's opinions of compliance normally certify only the house, not the estate in which it is located.
If the builder paid the Council the bond it may be the Council's resposibility now to use this bond to carry out this work.
If the roads and drains are okay right now then 10 years may not be a problem.
If there are known recurrent drain blockages or if the road is showing clear signs of cracking and settling there may be a problem, as this may be noted in any survey the purchaser commissions.
But again, this may only arise where its so severe that the bank places a lower valuation on the house because of this, i.e. it seems like a generic "estate" problem, which may tend to devalue all the houses in the area.
Hope this helps.
ONQ