In the case of the LP to CD and VHS to DVD transitions, the dynamic was different. Owning a shiny new CD or DVD was a status symbol, so consumers were willing to pay more. The quality of the user experience was dramatically better on the new media. Also, CDs and DVDs were priced higher than LPs or VHS, so the business community made more money off of them. Even so, it took decades for the transition to really happen-- and for some older people, it hasn't happened even now.
In the case of TV to DTV, there was a government mandate to get the transition done. Enough said.
In the case of the Apple III, there were a bunch of problems. It had Apple II emulation, sure, but that was "intentionally hobbled" (according to Wikipedia). There were some plain old engineering mistakes like circuit boards malfunctioning because they were poorly designed. The Apple II was Apple's bestselling model ever, as a percentage of the market. They've never again had the same level of success since Steve Jobs decided to torpedo it and start with something completely incompatible.
Did Itanium kill off Alpha, PA-RISC, and the rest? Well, sort of. Intel made threatening noises and those companies basically decided to fold. The fact that Itanium was later a flop makes the whole situation kind of funny.
The truth is, though, it probably wasn't economically viable any more for those companies to compete with Intel/AMD in high-performance computing. Intel's process technology is so far superior to anything they have access to that that kind of competition is a joke. And the HPC market is so small that it can't support the kind of investment in process technology that Intel makes every year. HPC clusters now are built with Intel or AMD's latest, not with PA-RISC.
As I said before, it's a matter of motivation. Figure out who the key stakeholders are, and get them on board with the transition. Give them a reason to upgrade, rather than just telling them to do it for the good of the galaxy.