Will they ever? Surely at some point there just wasn't enough light reflected off of dinosaurs skin to reconstruct anything more than scattered dots of light.
Scattered dots of light can tell us a lot! If you find a photon of a frequency that's only produced by, say, a CO2 molecule, you can prove that CO2 existed 50 million years ago. Ok wow, probably not too useful. Collect a bunch of photons, count how many indicate CO2 and how many indicate O2, and you can figure out the composition of Earth's atmosphere. All of this using single photon detections!
Theoretically you'd just need an enormous telescope to collect enough light to resolve an image. Though based on the features that modern telescopes can resolve on the moon ~1 light second away, it'd probably need a telescope on the scale of a galaxy
Nope! We can detect individual photons (and measure their properties) and a mirror can (nearly) perfectly focus and collect every photon that hits it. The frequency of detection events would change with the distance, but the frequency doesn't hugely matter, one photon per week is enough for science!
It is definitely possible that I’m missing something here.
But, for example, if we are trying to get an image of a dinosaur, and we’re only getting one photon per week, how’s that work? The dinosaur should have moved before the second photon is sent off, right?
You're totally right, it's me that's missing something. If you had something that moved predictably, say a whole planet, you might be able to get results by accumulating over a long period of time, but single photons would not be useful for imaging a dinosaur.