I'm surprised at the generally positive approach in HN toward Apple's recent announcements. Apple is about to have control over the user's system no one since mainframe-era IBM ever came close to.Not only they're about to move desktops/laptops into the App Store's walled garden, they are showing they can drop support for major technologies like Java or Flash if they feel like it. This is not good news for anyone but Apple, certainly not anyone calling themselves "Hacker".
The problem is that you're jumping to some serious conclusions. Nothing about the mac app store demo showed banning of applications from a different source. You're assuming that's their plan, but I don't think it is. The app store makes perfect sense from an end user perspective. One of the great things about linux are the package managers. A central location with lots of software that I can install from AND get updates from.
There is no flash on the iPhone for many well document reasons, so I'll guess you're referring to no flash on the new MBA. Given that any version of flash is out of date and a huge security hole as soon as it's installed, it makes complete sense to force users to go get the latest version when they buy their machine. It wasn't long ago that the shipping version of flash on osx had a huge security hole that made Apple look bad.
What I would like to see if Apple let Adobe put their flash player into the new mac app store. This lets Adobe manage the updates like any other 3rd party developer.
As a 'hacker' I look at what is. Right now my MBP works great and has all the support I need. If Apple does end up going down the path of locking out all other software and/or the ability to hack and develop I'll switch back to linux. At this point though, it's much ado about nothing.