Milky Way Races w/ Largest Presence in Andromeda

It wouldn't be odd if the ARKs wanted to hire on some carefully vetted krogan for the expedition since krogans are known to be able to survive in incredibly toxic enviroments and against incredibly tough creatures. The krogans would all be sterile so there wouldn't be any risk of them reproducing as far as the expedition knows.

A lot of the krogan outside of Tuchanka don't care for krogan because they don't believe they have a future so there'd certainly be some who'd have no problem leaving the galaxy. I could even see some of them being legitimately interested in being a part of this expedition since it would be a way for them to set their mark somewhere else.

If Bioware later down the line decides they want to bring back the krogan as a surviving race without re-treading the issue of their reproductive rate then a way could be similar to Okeer's with the babies being tank-bred. Could be an interesting way these krogan differentiate themselves from the krogan we've seen back in the Milky Way especially since tank-bred was something they were disgusted by but something these krogans might embrace.

It'll be interesting to see how BioWare deals with the Krogan.

There could be some modestly fertile females on the Ark ship ... Wrex might have seen to that. As I understand it, the genophage doesn't make all the females completely sterile, it just means that only 1 in 1000 eggs yield a living Krogan baby ... some females may be completely sterile, others may have some successful egg clutches, others may have mostly successful egg clutches ... with high infant mortality. If a female is able to lay 1000 eggs a year, conceivably a modestly fertile Krogan female could produce a new Krogan baby each year. Don't know about the Salarians, but that pretty much beats what humans can do ... given the limited lifespan and years of fertility of the human female, when compared to Krogan or Asari. 

As long as the Krogan don't kill each other off, there should be enough of them to make a difference, with respect to the numbers of MWG migrants. Living on worlds more hospitable than Tuchanka should reduce the mortality rate, to include infant mortality rate. Not being in clan wars or hiring out as mercs could also improve adult mortality rates. It just depends on how the Krogan respond to a different living environment and social construct.

It could be exactly as shechinah says, the Krogan are tank bred males and like the orphaned Vorcha raised by Asaris, have a totally different world view and social construct than what was typical of a male Krogan born on its home world.  Though I expect they would go through the same *ahem* growing pains as Grunt.

BioWare has had several years to think a lot of this through ... we'll probably be surprised ... I hope in a good way ... at how they do it.