I'm pretty sure "If you currently possess a Lancaster County Conceal Carry Permit and you are not a resident of Lancaster County, PA, your permit will no longer be valid upon expiration." means:
If you go up there before 6/1/2018, they will issue you an out-of-state LTCF that expires in five years, and it will no longer be valid after the five years.
So, head on up there and get your (last?) same-day permit.
Edited to add: My Lancaster County LTCF expires in May 2020, and I expect it will be valid until that date even after (if?) Lancaster County stops issuing out-of-state permits.