The best possible outcome is genuine reconciliation and agreement among all warring groups. This will be a difficult task that would require serious men who are sincere in their efforts. With enough pressure from the West and the realization on the elites' part, that they will lose everything might prompt a change in their behavior. This is the most hopeful outcome.
Abiy is the biggest obstacle. Unfortunately, the West believes there is no clear alternative leader that can replace him. The Emirate money and Turkish/Chinese are what keep in power militarily.
Other groups that will hinder any peace process include:
1. Oromo PP, this is the group that surrounds Abiy. Their support for him is strong. This is due to the fact they are now occupying the admin centers of the government and military. They are amazingly corrupt and are robbing the country blind.
2. OLA. Abiy tried to coopt OLA with the promises of positions within the government. They flatly declined his offer. Their only interest is free Oromia. They are most active in Western Oromia and Borana regions. They ran most of the rural areas and moved as they wished. Abiy tried to suppress with regional forces, ENDF, and drones, but it is winning OLA more fans.
3. Amhara: The Amhara are most aggrieved. They sincerely believe Abiy wouldn't have defeated TPLF without their sacrifice. Their grievances are not only with Abiy. They believe they have unfairly been blamed for everything that went wrong in Ethiopia since the days of Melenik, and as such, every new admin would hit them hard. The Amhara can be divided into three groups, the first group wants to oust Abiy and revive the centralized Ethiopia where they ran everything. The second group has given up on Ethiopia. They come to believe a separate homeland for Amhara is a must. This group supports the Fano movement. The third group is within PP. They once believed they could change the government within, but that hope has faded and many are leaving PP, and with their departure, PP has essentially an Oromo party.
4. Ethiopian army: The institution is not what used to be. It is highly dependent on conscripts and it is beginning to look an Oromo party. Most generals and colonels are Oromo. It is no longer a reflection of Ethiopia. More and more soldiers are defecting every day.
5. Tigray; The peace process between Abiy and TPLF has not worked out well for Tigray. From TPLF's perspective, their lands are still in the enemy's hands. Aid is barely coming into Tigray. They appealed to the AU to help in implementing the Pretoria Agreement. TPLF still has two hundred thousand armed forces. Abiy wants them to join the war, but so far, they have wisely decided not.
6. Eritrea: Afwerki feels crossed. He believed in a centralized Ethiopia with no ethnic borders, but he made the mistake of trusting an Ethiopian leader. He was blinded by his hatred for TPLF. I believe he is no longer vested in one Ethiopia whose leaders he can manage.
There are three possible ends. The first and most difficult is what I mentioned above, true peace among all parties with acceptable political settlement. The second is an apocalyptic end to this ailing empire, a war to end all wars where new countries will be born.
The third is a new alliance among Highlanders and Eritrea that can overwhelm Abiy and exile or kill him. The Highlanders and Eritrea are politically savvy enough to put their differences aside in pursuit of a bigger goal.