What kind of tone do you want if a continuation to andromeda happens?

A little bit of both really I personally felt that the trilogy felt a little too dark sometimes and I appreciated the fact that MEA didn't take itself to seriously which was kind of why I enjoy it as much as I do I think. Sure it was disappointing that it didn't get DLC but that hasn't stopped me from enjoying it. MEA still had it's fair share of dark moments too though it's just a case of finding a good mix.

I'd like a mix of both, but a more linear game so that the pacing between dark topics of the game and lighthearted moments doesn't get skewed by the order in which the player happens to do the quests. The conversations with NPCs still need to get "more sensitive" over what the player has just done in the game... a very difficult thing to do, no doubt, the more "open" the game is. It is jarring when a bug or just lack of sensitivity in a conversation trigger causes a quip to happen utterly out of context.
Dark humor" can work, but only if the timing is spot on. Otherwise, serious moments should be left as being serious.

I remember them saying the story may take place over more than 1 game but I don't remember them saying anything about it being another trilogy though but I think they're trying to keep things more open due to how ME3's endings ended up getting received. I never had any problem with them but I can understand why others did. I think the trilogy part was just an assumption people just made due to the first 3 being a trilogy.

It should be a mix. I don't mind moments of humor mixed into the game, but I just hate corny stuff. There's a huge difference. A lot of the stuff in Andromeda was just corny. They really just need to have it be it's own response choice like sarcastic Hawke in DA2 if they continue along the same lines.

I like for the next game, if set in Andromeda, to be dark. The beginning takes place shortly after the events of MEA with the kett going on the offensive by destroying the nexus. The main character is tasked with going to another cluster to get help to deal with the kett

Ryder has grown much throughout Andromeda. Just compare the way that the Initiative's leaders treat Ryder at the beginning and the end of the story; it was an gradual process, but remember how Addison refused to Ryder as "Pathfinder" in the beginning, but naturally uses the title once you create Prodomos.

Following the pattern of the Hero's Journey he or she will have to face some temptations (e.g. Luke went after Darth Vader in the Empire Strikes even though Yoda told him not to, where he is then tempted even more by Darth Vader himself, Shepard was reborn as part of a group that used to be the bad guys and needs to accept their gifts in order to fight the Collectors, Neo must choose whether he takes the red or the blue pill, and later let go of his previous sense of reality in order to make the jump)

I would expect there to be a dark and sinister revelation, not right in the beginning, but towards the earlier phases to the mid of the game to the nature of either the Andromeda Initiative or the Ryder family, that puts into question everything that Ryder believes in.

I also could imagine opportunities to make more deals with the devil, like selling out the Angarran altogether to secure the place of the Milky Way races.

I wouldn't say that it has to be entirely dark, but Andromeda 2 would have to relate to Andromeda like The Empire Strikes Back to Star Wars, simply because it follows the same pattern of story telling, just as Mass Effect did.

The curious thing about Andromeda is that Ryder doesn't really have a mentor (Luke had Obi-Wan, Shepard had Anderson, Neo had Morpheus...) You could count SAM in that way, but SAM is rather Ryder's divine gift, the thing that made him or her special (Luke had the Force, Shepard was already an exceptional warrior at a relatively young age at the beginning of the story, Neo had the power to manipulate the matrix and bend its rules). Kora could have filled that role, but then she would not have been a viable love interest anymore. Thus, she was way to caught up in her own problems. The siblings did not learn that much from their father and he's already dead. Who else? Jaal? Addison? Hm. Not really.

A mentor figure that is possibly on the horizon for Ryder is Ellen Ryder... although she clearly would not be a combat mentor.  Still, of anyone she would know Alec Ryder the best and was involved also in SAM's development.  Although, Alec was a person who kept everyone else at a distance and did not confide many of his secrets, he seems to me to have been the sort who did confide in his spouse.  Once awake, she could be the one who, in a more human way, facilitates tyoung Ryder's access to Alec's memories.