To date, the largest LCD you’re likely to find on a DSLR measures about 3.5” diagonally. Even among pricier medium-format DSLRs, the largest LCDs top out at 6 x 7 cm (2-1/4 x 2-3/4”). The reason we can’t have larger LCDs has nothing to do with technical limitations, but simply the fact there’s physically no room for larger screens, even the touch-screen variety.