Because you don't know anything about how camera sensors work ?
Please try to make HN a corner of the web where participating benefits everyone. Perhaps a breakdown or rationale as to why a camera sensor of this resolution will never be that small?
Smartphones have become ridiculously large in the past years, but I think you are a bit too pessimistic if you assume that they fill fit two feet sensors that soon.
Even if it could, it wouldn’t be useful because of diffraction.