The concerns seem to include:
- 3-point edit system
- tape I/O
- log & capture
- 'child-like' UI
- being able to run FCP and FCX concurrently
- Color correction tools
- rewriting tutorial material
- support for capture hardware
- no track lines
The least important points I'd say are the UI style and relearning. The UI is not that much different from FCP in terms of function or layout. It just behaves more intuitively. Final Cut Pro does things wrong and learning the wrong way doesn't make it the right way.
Having to remake tutorials is a plus for book writers because they can make new ones and as far as teachers are concerned, less of having to answer what the hell messages like "File Error: unknown file" mean.
The UI style being child-like and unprofessional is plain silly. These people still use aqua Mac OS X and don't seem to have any problem with it. FCP uses an archaic UI just like Shake did and most of the legacy apps and it causes problems/glitches. Good UI design makes a difference to productivity. No disappearing panels or messed up layouts or closing a panel by accident or clicking in a gap between them. Putting on a drab suit doesn't give you credibility, let people judge you based on what you do.
Given that the stage demo showed a project transitioned from FCP to FCX, it's probably safe to assume it's capable of creating the same edits so 3-point edits, track lines etc shouldn't be concerns but obviously all will be clear in the release. Same with the current CC tools.
I highly doubt that Apple will drop plugin or hardware support, although legacy capture/export could be dropped. Their decisions will be based on what the industry tells them and not people with old HDV cams. If the industry has moved primarily to digital capture, there's no need for tape input/output. Backing up to tape (e.g LTO) is a different thing entirely and doesn't need to be handled by Final Cut.
Being able to run FCP and FCX together would be for people who just want to test it first or use it alongside the current workflow. It would probably be wise of Apple to do this so people can transition projects.
The important point I think that was clear is that they've listened to feedback from the professional users and delivered a huge number of big improvements. If there's anything missing that's needed, they'll get to know pretty quickly. At the end of the day, we're talking about NLE, it's not exactly the most complicated set of software tools in the world. You have input clips, chop them up and correct them and output clips. It's pretty difficult for a UI change to bugger that workflow up.
I actually don't get where the discontent is coming from. For once, Apple aren't pushing a new phone or tablet in people's faces, they are putting quad core i7s in laptops, bring in standardised external PCIe and giving some much needed attention to professional apps and not iApps. To me, these developments show there's still a desire at the company to provide powerful tools to high-end users. I'd say there's definitely a bridging between consumer and professional lines at Apple but remember when smartphones used to be owned exclusively by suit-wearing corporate types?
It's not always a bad thing. Pros are shooting TV shows on DSLRs, does that make them a bunch of know-nothing kids? Of course not, people use the tools they feel are right for the job and it's up to the software makers to play along.