DLR doesn't even have biometric scanners and instead uses barcodes for ticket media so even if FP+ were in the works for DLR it would be a real long while before it happened.
Personally, I don't see it happening. With Magicbands Disney wants to track guest behavior and give guests the time and opportunity to spend money on dining and merchandise. That's not really an issue at DLR. Everything there could pretty much fit inside Epcot. Plus, limiting advanced FP+ reservations to resort guests wouldn't work because there are only three resorts at DLR and they don't have issues filling in rooms. It would be an absolute mess if just about every guest that walked through a park gate had to be assigned FP+ times day of. They can't risk anyone else making FP+ reservations in advance not knowing if they're going to be in the parks without a resort reservations.