Our eyes will age like the rest of our bodies, but those changes shouldn’t ever get to the point where eyesight can’t be normalized for a given activity by a good optometrist. IMHO the solution isn’t a bigger iPad, it’s a better eyeglass prescription. As we age, it may very well take more than the usual “new prescription every two years” to keep pace but should be do-able. In some cases, older people might find that they have specialized prescriptions for different activities to accommodate the changes in their ability to focus…i.e. glasses for reading, TV, computer, shooting, driving, flying. I do.
Other consideration with age is cataracts. That will change color perception, acuity, and focusing. Cataract surgery does a remarkable job of fixing those problems, will usually simplify corrections. If one finds, as we age, that vision just isn’t as sharp as it used to be, it will usually mean that the eyes have changed enough that the prescription is no longer optimal, or cataracts. Both are fixable.