1. Most anime fans know that Taki & Mitsuha have a cameo in the 'Weathering with you'.

2. If you have watched '5 centimetres per second' from the same director, the story is likely to have a more lasting impact (the ending is quite different from Your Name or any other Shinkai movies)

3. I completely agree that a sequel would be interesting, but I doubt Shinkai would be ever treading on this path. He will in most likelihood, not try to piggyback on an existing success.