I don't understand. Those points that favor the PowerBook are still valid for the iPad.
- Consistent app: there are more apps designed for the iPad than, let's say, Android tablet or Windows UWP
That I agree to an extent. Yes there are more quality iOS apps than Android apps. I do however have a lot more freedom when it comes to my Windows laptop than with the iPad.
- Blistering speed: I think it's easy to say the A12X is still the fastest and most efficient mobile chipset
Completely true but I can't take advantage of this. I don't edit videos and I don't play video games. I do Software Development and I can't use the iPad for that. So basically that fast chipset is non factor for people like me.
- Built-in networking, file-sharing: Wifi and bluetooth, coupled with iCloud, Airdrop, Handover, etc
Works if you have Macbook. I own Windows laptop and iTunes for Windows is just awful. The fact that I cannot share files via Bluetooth to my iPad is annoying. Overall I find the files sharing stuff quite cumbersome with iPad. It's far easier with my Android phone. The fact that it does not have micro sd is huge turn off for me too. I do not want to use the iCloud because I want to be able to access my files even when I don't have Internet.
- Trackball: superseded by multi-touch
Maybe it depends on whether you have iPhone or Macbook. I find the iOS gestures quite not intuitive and quite difficult to do on an iPad. Quite often I want to do one thing and I get another one. It's really annoying and just frustrating. Things like that basically prevent me from seeing the iPad as a serious laptop replacement. For me it will always be a good device for going paperless as it has touch screen and a pencil.
Honestly I just checked my screen time for the iPad I have. In the weekends I almost don't use it because I have my laptop with me which I find better for media consuming, browsing and typing. I use the iPad solely at work for taking notes during meetings. The moment I go home though the iPad just stays in my purse and does not get used.