"Should the Hobie 20, 17 and 18 classes make any local rules changes now that the boats are out of production?"
Yes, the class association should start discussing the future, or call it the Hobie 16 class association

"Should the Hobie 16 class embrace the spinnaker? (Its just a rhetorical question in this list (grin)?"
Maybe not, eventually (5 more years best case?) the 17, 18 & 20 will need something else.

"Should Hobie regattas go back to 5 boats equal a class race… otherwise.. go home?" No

"Should Hobie regattas score hobies that don’t make class(5 boats) in Hobie Open?"
A portsmouth class within a Hobie regatta? now that's interesting, in light of reduced numbers and the future of the dead boats, not a bad idea. So many times I see a guy who sailed 17 when only two or three showed up, not do well on Saturday and be ready to pack it up after Saturday night's dinner, no chance of winning or improving place, no doubt a frustrating situation. Maybe I should re-think the 5 boat minimum answer.

"Should Hobie regattas run Open Class?" sigh

"Should Hobie regattas run F18 class?"
Definitely, non-Tigers wouldn't get Hobie points, and how many Tigers are actually "chasing points"?