[OT Spoilers] Finished Andromeda, Bioware missed out on a perfect ending for OT

Having played Andromeda I can't shake the feeling that Bioware missed an opportunity for a good ending for the OT. I know it's all in retrospect because they haven't even thought of another galaxy until after ME3 has been finished but it would have been smart of them to have thought of a larger arc.

In my opinion, the Crucible should have been discovered to not be a weapon, but an inter-galactic ark to save the Milky Way. Protheans were simply unable to finish it before their destruction.

The ending would be all species on the Citadel being evacuated to the Crucible Ark set for Andromeda and Sheppard deciding to stay behind to enable their escape. This would end the Sheppard arc nicely in a self sacrifice to save the galaxy from extinction.

This would lead to Andromeda better as the possible threat of possible Reaper appearance would still linger in the new world. No special space child and his stupid explanations needed. The reapers were at their best as Lovercraftian monsters that needed no motivation for their action. Also we could use the Crucible as the new hub instead of the Nexus.