If we go with the above (#4), then Martin Grove is an underground station. You have 300m to elevate the line over Eglinton. If the station has a mezzanine, and you start from 8m below ground, then there's not enough room to become elevated before the Eglinton intersection (at its current location). If there is no mezzanine, or if the mezzanine is located below the platform, then it could likely be done. This all depends on whether the line is built with cut-and-cover or TBM. With cut-and-cover, it will be shallow and the above is possible. If TBM, it would be too deep to surface before Mimico Creek. Likely they are planning TBM, which means it would have to be underground all the way to Renforth.
It is also possible that the Eglinton-Eglinton intersection is moved to the west side of Mimico Creek. As I pointed out before, if you can get yourself between the two Eglintons, there is space through the north end spans of all those bridges to run the LRT at-grade, or marginally trenched. Of course, if it's TBM, this still wouldn't help and it would have to continue underground to Renforth.