It is definitely possible for any two countries to reconcile with each other, even after there has been word of genocidal thoughts between them - the key, however, is time. Two countries would never be able to see eye to eye in the moment of hatred that leads to genocide, but generations later, this is not the case.
Reconciliation happens on occasion, but not always. It was hard for Americans to accept members of the Confederacy after the Civil War. It was hard for citizens of the Soviet Union to get over Joseph Stalin's murder of tens of millions of political opponents. Some places simply broke away from a mother country like the former Yugoslavian countries during ethnic cleansing in the 1990s. Reconciliation is feasible in some countries but not in others depending upon which examples you choose to study.
No, reconciliation is not feasible in countries with genocidal activity, because any government or group of people that would participate in genocidal activity would not be reasoned with. Those who participate need to be treated like ruthless bullies. They need to be shut down with force. They cannot be talked to because they are too extreme. The country needs to start over.
Reconciliation is hardly feasible in countries with genocidal activity because there is too much animosity. That's why Israel was created as a homeland for Jews so they could flee Germany if they wanted to. Reconciliation wasn't feasible during the Balkans' ethnic cleansing of the 1990s which is why Yugoslavia split into smaller countries.
When a country goes through a period involving genocidal activity, there's no returning from that point in many ways. For instance, reconciliation usually becomes nearly impossible at that point. The victims in these situations will never forgive the inflictors. With that in mind, genocide needs to be stopped as soon as it begins.