Surely Internet Recovery will know what was shipped on your serial and only allow that version to be installed by IR - but any OS that shipped on your model should be runnable, so if you had a 2012-model MBP that shipped with Mavericks (but earlier units shipped with say ML) then I'd expect you to be able to install any of:
ML (by bootable USB eg DiskmakerX)
Mavericks (only option by IR)
Yosemite (by bootable USB eg DiskmakerX or by App store update etc)
Surely this must be true as any original (say 2012), models that shipped with (say in this example), ML originally must be able to IR back to that - even if they had been updated to Yosemite since...
This could of course change in the future, Apple might choose to push out a concurrent FW update that means IR back to original would be impossible but that would be high-risk, however they could also update the IR records for that device and make it IR to the later version once it has been installed. High risk as I say but technically quite easy.