IMO it's hugely different, at least in the server space. In the 90'es _all_ servers ran on proprietary platforms (OSes and micro-architectures). To succeed with an alternative, you had to convince your OS vendor (Microsoft, Sun, ...) to port. The most famous attempt Windows NT (ran on x86, PowerPC, Alpha, and possibly more), but the effort fizzled.
Today, the MAJORITY of servers run Linux, even on Microsoft cloud platform, and a significant part of that is using primarily open source (eg. "LAMP"). If, say, RHEL supports your platform, it's fairly easy for most to move.
Yes, it's not easy to migrate, but it is _way_ easier than it used to be. Now, non-server application is a different story.
Today, the MAJORITY of servers run Linux, even on Microsoft cloud platform, and a significant part of that is using primarily open source (eg. "LAMP"). If, say, RHEL supports your platform, it's fairly easy for most to move.
Yes, it's not easy to migrate, but it is _way_ easier than it used to be. Now, non-server application is a different story.