Too Long; Didn't Read
There will be sort-of 3 versions of software platforms with backward compatibility. Small-And-Middle-Scale-Companies (SMSC) are the ones in trouble because they have to act quickly to please a client or give stiff competition to its competitors. Developers should always be biased for future(new features) rather than past(old versions) If you are a Developer, always make sure you can support all of the older versions Product Manager is asking for, without compromising any of new features.