I wouldn't even think about a subscription until we know exactly what PG2 will look like.
For me, there are certain things that have to be there before I would pay for this game a second time like a proper and sustained tournament structure with statistical collection, rankings and handicaps, for instance.
New course would need to be introduced regularly with no charge on a higher subscription payment but a small charge on a lower subscription payment.
Right now, we need a solid statement of intent from PG that PG2 will actually happen and when.