With respect to Ran, it has been hinted (in OVA 9) that she has a lot of patience in waiting for the real Shinichi to return. Although she may initially feel shocked by the truth, if her love for Shinichi is still adequate, she will understand his predicament.
With respect to Kogoro, my hope is that he withdraws from public life for a time and enters rehab, so that he can kick his drinking and/or smoking habit and thus make Eri more willing to reconcile with him.
With respect to the other DBs, it has been hinted by someone on another forum that at least one of the DBs is very mature and would thus be able to understand Conan & Ai's predicaments.