But, you DON'T have to maintain the architecture. Apple had overall compatibility with MC68000 through 68040, and swapped in PowerPC in the nineties, and a decade later Intel (Core generation), while maintaining overall code compatibility. They're about to move to ARM, because the low-power devices on that base have become ubiquitous.
Heck, the NeXT group had a single codebase that could build to several architectures, and SPARC kept going largely because of Java (and its cross-platform compatibility model).
For user experience, the game consoles haven't suffered from the variety of non-Intel architectures they employ.
What seems to matter for marketability, is to have a vertical corporate entity that handles hardware/firmware/OS/software all in one place. Intel (they build boards) and Apple are thus dominant, with Broadcom in the background.