Unfortunately, it's not entirely clear that Volvo itself will survive unchanged into the future. In fact, Volvo is working on Chinese plants as we speak, with the Chengdu plant underway and another plant in the works. So if the re-imagined P1800 were to be built, it'd probably be built in China.
That's not necessarily a bad thing, but so far, we haven't seen much come out of China in terms of automotive hardware that we'd like to put in our own garages. Ten years ago, we'd have said the same thing about Korea, but Hyundai/Kia has changed things dramatically.
Here's hoping the Geely-Volvo union goes that well, and that this modern P1800 sees the light of day, even if only as a concept. The P1800 has long been one of our favorite exteriors on a car (even if the rest of the car leaves something to be desired), and from what we can see in these sketches, the new one could be, too.
Re-imagined modern Volvo P1800 sketch for 50th anniversary