Unlikely MRT plan as it's still too early in the planning stage. According to URA masterplan, there is plan to connect lor harlus via probably an expressway from pulau punggol timor. See map
http://www.ura.gov.sg/uramaps/This masterplan 2008 is already outdated. URA plans to update the masterplan. Yes, there are plans to link Punggol with Pasir Ris via Lorong Halus and Paris Ris Farmway 3. Residents staying in East Punggol using KPE can use that road to get onto and exit KPE. This will save time and reduce the congestion.