I actually looked up not that long ago(like 2 days ago) on my usual "study the lore of a game series before I buy it" tradition. And I found out Krogan and Asari both at least can live to 1 thousand years. So there is pretty much a large timeframe for which she could be on the planet. Online said Liara is 106 years old. So I will say she has plenty of time to go to the planet so I couldn't really tell how old she is on that teaser. Could be 999 years old in that teaser.

I say a couple hundred years as Shepard story is over. We saw Liara in the trailer yet she looked much older. So given the asari slow aging. She looks more like in her Matriarch phase. After all when you meet her, she says her people would consider her no more than a child so am taking this as at least a couple hundred years have passed since then. So if they were gonna bring Shepard back for whatever reason (besides fans worshipping them) they would either be a ai or another lazarath project. But I still say for the third time in this that at least a couple hundred years have past

We don't know how old krogan or Asari can get. That's up to the writers. But people think that Asari can get over 1000 years old, but krogans around maybe 1000-1200 like drake. Some people think that in the next game Wrex and Aria will come get in. What sounds awesome because of their past.

I think so to but there are still players who don't wanna let go over Shepard what is also understandable, they didn't give him a happy ending. What i wish myself is that we can play as either Ryder or Shepard in the next game (Maybe also the old crew to give Shepards romance live also a happy ending) and after that i would say Shepards story is officially over. Because we all know this topic when it comes to Shepard is pretty tricky. And by the way liara must be around 700-800 years old because fans think that she will come to Andromeda. But honestly we can't tell, at least speculat. Because we don't know the planet she was on. The only thing what we know is that the planet has three moons. And i think i saw in the trailer even Ryder in the background...

Where do you think you saw Ryder?

At the end of the trailer when liara looks to the little Squad, but it can be just a guy with the same armor.

@Shadow Freddy 544 we do know how old asari and krogan get it’s literally stated in the codex

And how old?

Sy im at work right now, don't have the time to look after.

Krogan if I remember right live over 1000 years give it take for the krogan asari live up to 1000 years turians live same as humans 150 years salarians 85