The defence can always apply that the prosecution should be stayed; we still have a plea that continuing is against the interests of justice, rarely used; but I bet it won't get them far. Their best line is a bit of good cross-examination. What is worrying is the possibility that the offences alleged have some striking similarity which independent complainants remember.
It's practically unheard of for complaints of this nature to be brought to trial this many years after the alleged events. Cases of incest are often brought decades later but that's usually because the victim, often prompted by fear that young members of the family are now being so assaulted by the father or grandfather, decides to speak out. And, of course, advances in DNA testing may mean that old cases of rape can be prosecuted when previously they could not.