Regardless of the lack of conclusion to the two high-profile sex scandals at this point in time, I think the damage to the govt is done. But it can also be argued that the investigations into these two senior persons demonstrated the will of the PAP Govt to right the wrongs. Just like WP sacking YSL.
MRT is indeed a major issue affecting the lives of many Singaporeans, HG included. But I expect the YSL incident to be the main talking point at this BE, and I'm sure PAP would, and should, make the most of it politically. Afterall, this is a BE and it's in some way a "local" contest. HG residents obviously are faced with many issues that are across the nations, but there is no running away from YSL incident hogging the limelight at this BE.
WP must have already devised a containment strategy. Unfortunately, they'll be on the defensive for this one.