As far as I know all that will happen is you will lose the extra facilities membership give.
The date however is an interesting point. I have been blipping for just over a year but I have had 3 joining dates .
- The date when I joined 17/12/14
- The date I began commenting on my wife as a guest sometime back in 2010 I think.
- Now it shows the date I became a life member.
I have decided to celebrate my own milestones no matter what blip thinks they are.