Current Macbooks aren't especially repairable so I'm not sure why you'd expect ARM ones to be.
And merging iOS with OSX would be odd given that they've just split iPad OS out from iOS. Why would you have phones and laptops on one OS and tablets on another?
Current MacBooks are more repairable due to the fact they share some basic bits and processes with existing X86 laptops,so 3rd party repair companies still can do stuff which Apples refuses to do. Move to ARM,and Apple has even more control over the "repair process" which means they become even worse,as it means even more proprietary stuff.
They are the same basic OS underneath,just because the UI looks a bit different does not mean much. The whole point of moving away from Intel,is so they can have one basic underlying OS for ALL their devices,hence saving them money. They can leverage designs for laptops from their tablets. Apple sells far more tablets and smartphones than laptops,and desktops. So think of maintaining a separate OS X ecosystem and hardware design as an additional cost for them. Their margins are dropping,so its all about cutting costs. Using an ARM CPU,they can leverage the same design teams for their phones and tablets,and the same OS,means the same software optimisation and development teams. They can cut out Intel and AMD,and make the same amount on cheaper ARM based hardware.
Apple has a history of driving down costs. They tried to scupper the UK based Imagination Technologies,who supplied most of the IP for their GPUs. They first all of a sudden stopped licensing it,then opened a new development centre nearby in Cambridge and started hiring away their engineers.....all to save a few million USD a year in licensing. All it lead to was a Chinese back consortium buying up the company,Apple obviously not getting as much headway,and then again licensing their IP. All they did is just cause Imagination to become foreign owned,people to be fired,and I doubt they saved much if any money.
They make a ton of money selling smartphone and tablet apps through their appstore. As long as the hardware works fine,the current Apple laptops and desktops will have a longer lifespan than an iPad,ie,just like most laptops. This is bad news for companies such as Apple,as it means less repeat sales,so they are doing everything to go against this.
Better to sell tarted up tablets,as they can lock you into the smartphone/tablet ecosystem which means generally shorter lifespans,ie,for the most part tablets and smartphones are more disposable.
Plus Apple has said they want to be seen as a "services company" as they see growth in "services". So what do you think will happen longterm to "OS X" then? It will eventually become an offshoot of iOS/iPad OS. Think of the MacBooks as simply being an iPad with a keyboard eventually and that is the future. They will increasingly push for software to be purchased exclusively through a dedicated app store. They will slowly ease it in,so people don't get annoyed,but it will be what you will see in a few years. If Apple is making billions from their iOS app store,then OFC why wouldn't want their "desktops" and "laptops" to do the same?? They want a cut of all software sales on their platform. They can sell the move as being for "security" and needed for "optimisation" for the new ARM based platform.
I am sure some of the people really into the "high end" Mac Pros are going to complain,but Apple has been updating those far less frequently and bumped the price up,with less than fantastic hardware. They are interested more in the casual crowd,who are better and quicker repeat customers.
