If he would have done much different, I don't know. I also guess his main concern with Flash was, that he couldn't control the proprietary plattform. The flash player could have been improved ... but Adobe would have been still in charge.
Oh, the irony.
The original IBM PC had pretty open hardware and software, both a little unintentional. Hardware-wise they published everything so add-in cards and more could be developed. Sofware-wise they didn't hold Microsoft to an exclusive agreement for PC-DOS so MS-DOS could come out.
Later they tried to close the barn door with very locked down hardware with the microchannel bus and IBM's own operating system OS/2. But it was too late...
I actually think Apple and their customers would be more successful with open hardware. When they went from powerpc to intel with more generally compatible hardware, I think that was great. Now they're reeling it back in, and I wonder if they'll be following the same path as IBM did...
Phone ... smart phone opened? From Nokia, Newton, palmpilot, windows phone, ...
The question is whether the phone business model can bring it to desktop and conquer there. Wonder.
I like my phone is walled garden and I can take risk of my collections of pc.