You skipped the bit about differentiation: if, for example, photoshop didn't keep improving, do you think the gimp would never catch up? I think you could find lots of examples where today's open source version is better than an x-years-old proprietary product.
The only way it realistically can realistically happen if is the commercial product is not being improved (i.e. differentiated) any more. Your example is one of these - standardization is related to commodification.
I suspect also that user-facing apps are easier to keep improving, because the user is right there, and always has more needs that could be served (e.g. text editors will evolve til they can read mail; those that can't will be replaced by those that can). Non-user facing apps tend to be defined by their environment, rather than by users - although, any component that creates a benefit that the user wants more of will keep being improved (from Clayton Christensen). e.g. databases, CPUs.
The only way it realistically can realistically happen if is the commercial product is not being improved (i.e. differentiated) any more. Your example is one of these - standardization is related to commodification.
I suspect also that user-facing apps are easier to keep improving, because the user is right there, and always has more needs that could be served (e.g. text editors will evolve til they can read mail; those that can't will be replaced by those that can). Non-user facing apps tend to be defined by their environment, rather than by users - although, any component that creates a benefit that the user wants more of will keep being improved (from Clayton Christensen). e.g. databases, CPUs.