I'd like to stick with Ryder as well.
1. Ryder could transition from Pathfinder to a defensive/offensive stat (maybe military of some sort) in Andromeda, now that worlds have been established.
2. Kett. They are here to collect genetic material, numbers, improve their race. For what purpose? Time to find out what they are up to, since their interest in Rem-tech, or conquering is not their purpose here.
3. Kett could probably know about the Reapers or be at war with them, in their Kett system, reason for wanting to be a superior race. Reapers existed in the galaxy looooong before anything. "They are more than we could comprehend"..so...possibly they must know about the Kett. 50.000 years is plenty of time to explore other systems than the Milky Way.
4. Reapers could be easily be behind the Scourge. They probably wanted to prevent more systems from development, because too many systems to harvest. LOL Sooo, they came, saw the terraformers/life creators, they stopped them before remnants had a "mission accomplished" in the system, and then the Reapers left. They never came back since they knew they interrupted the "Creation" in Andromeda.
5. Geth. If they had an "Ark" (which they don't need to travel, except for a good ship) and if some left Milky Way, they could be already settled on any planet in Andromeda. They don't need terraforming, and they can stay hidden and build up their world. As Ryder explores further, he could simply bump into Geth on one of the planets.
- if Geth left during ME2, they would probably be hostile with the Initiative if they were discovered around Andromeda
- if Geth left after settling terms with Shepard (ME3), etc. then they could probably have some information about the Scourge/Reapers, since they interacted and have been upgraded with the Reaper code. They could know something we don't.
- also Geth could be useful against Kett. Maybe machines cannot be exalted in case we go to war with the Kett. A good advantage.
- Geth could also be able to provide answers to whats going on or what happened in Milky Way.
- Geth would be more capable to interact with Remnant machines, and learn more about them, maybe even learn how to create life and then we could exploit that. (but that would probably be like clone wars LOL)
6. Settled planets to be developed. Established councils (on Meridian), really cool trade hubs, mercenaries, information traders, smugglers, all that stuff for extra content, action, tension.
7. Maybe try to establish long range communication with Milky Way. Let them know (if possible or if they still exist) of our success, situation, struggles or even encourage them to migrate to Andromeda. Let Milky Way know about Rem-tech, their "creation" capabilities. But that could be risky, since Reapers could intercept communications. idk..debatable.
All in all, i really hope for a trilogy. I'm not saying No to DLC/ expansions as long as they have independent story missions, but clearly a NO to DLC that concludes game stories in pieces released at certain time intervals.