Thanks so much for this post. I'm going to take a crack at your questions, and please let me know if there are any follow-ups as I'm sure my answers will probably make more sense after the beta of Gantry5 has come out.
But will Gantry try to update to 5 on a template of joomla version not supported?
No, it will not. For all intents and purposes, Gantry5 is a completely different extension from Gantry4.
One of my templates I used rocket install of 3.3 and upgraded to Joomla 4...will I have to reload this template with an updated template to capture the abilities of Gantry 5 (Voxel is the template I'm using)...
Existing templates will remain on Gantry 4 as they would have to be remade from scratch for Gantry5. This doesn't mean we're ruling out potentially coming out with a reimagined Gantry5 take on the basic concept of an existing template, but there wouldn't be a direct equivilant the way I think you're describing.
The best way to think of Gantry5 is that it is a whole new framework. We've redone everything from the ground up for the Web of tomorrow, where Gantry 4 (while still quite powerful and more than capable of handling the needs of a modern website) is made on an entirely different base.
How is the testing with Gantry 5 and the google launch of it's DoDo Bird
algorithm going to work together for mobile friendliness, speed analytics, and all that fun stuff? (Dodo Bird is my loving name for the murder of sites it will cause April 21st...the next one I will call Albatros and everyone on their ships/websites will look longingly at the bird that can only fly and is chased by mariners...if it lands it's dead in the water...if it flies it is unattainable...
While I can't speak from any place of authority on Google's algorithms (very few people can outside of Google), I can assure you that Gantry5 is being built to meet or exceed standards for mobile friendliness. It has a new responsive layout system that is a touch above anything anyone else is doing right now.
Just worried I will have to rebuild a bunch of stuff I just built...
If you intend to keep using the same theme, you won't have to redo anything at all. Gantry 4 themes and templates will remain Gantry 4 themes and templates. We aren't by any means going to stop supporting (or even doing regular updates for) Gantry 4 in the foreseeable future. We have over 200 Gantry-based templates and themes in our library and every one of them is going to be supported for quite a while.
Even with Gantry5 beta so close at hand, we are still doing updates for exisitng templates and themes. Even today we are releasing a batch of updates, and this won't stop after Gantry5 launches.
If, however, you want to take advantage of Gantry5, yes... there may be some retooling required on your part with a new template or theme. Gantry5 is different, and this is where backwards compatibility comes into play. At this stage, it's still early and beta is not by any means being promoted as a production-ready build. We welcome you to dive in and give it a look when it comes out.
The following users have thanked you: Twiggliscious, MrT