This is probably going to come down to a matter of symantics, where we ultimately feel agreaved at arguing over stuff we probably mostly agree on! But, lets get on with it!
Mike.. all you're doing there is showing the difference between the analogue structure of the film, and the pixel based nature of the digital camera.
Pretty much, yeah. I'm going back to first principles; without clouding the issue, compounding simple detail 'resolution' with overall 'Image Quality'; they are not one and the same, and you know it.
What is the smallest detail of the 'scene' that can be resolved to image?
Analogue nature of film, you have already admitted:-
You may need to enlarge more to show grain in a low speed 35mm image than you do to show pixelation from a D3200, but that is all. The noise levels are pretty intrusive in either case at those magnifications, but the random analogue nature of the film "noise" will always appear smoother tonally.
So how much more enlargement, before you see pixilation or noise? I think that is the question here, and then; When you agree the more random nature of film grain, provides smoother tonal transitions... how much more 'fine detail' might that allow to be seen?
By my rather crude empirical estimation, I take content of a 35mm frame, and enlarge it; well, its on screen at about 10x7" at the moment... original frame was 36x24mm, crop is aprox 4.5x3mm.... something in the order of 50xmagnification.
At that magnification 24Mpix full-frame digitisation has pixilated out, and detail is indistinct, edges & lines leggo-bricked.
Same magnification, 1,500Mpix full frame digitisation, is showing grain, but rendering edges & line in that grain, sufficiently smoothly to be able to pick out 'detail'.
Similar magnification applied to 100Mpix & 17MPix. again, there is some grain still in the higher MPix scan at that magnification, but, it is still rendering edges and transitions more 'discernably'.
Looks Horrible? The grain is 'intrusive'? YEAH! I dont dispute you. But you cant argue that the edges and shapes ARE rendered within it, the 'detail' has been 'resolved'!
Of course it matters.Lens definition is what limits small formats Mike.
I think it limits ALL formats... if we are honest; it is merely a question of to what degree.
Larger format, the less multiplication needed to put the scene on the sensor. Less multiplication, less any error is going to be multiplied. Back to basics, back to first principles.
But that's to take the topic off, again, into tangential argument of image quality, not simple image resolution, and a sub debate on what is more important, lens resolution or camera resolution... to wit cutting to the chase, the answer is both; Have a lens that can resolve more detail than the sensor, you ent going to get it. Have a sensor that can resolve more detail then the lens, it ent there for you to get.
Which takes us to a suggestion we are likely to agree on, which is that overall image quality is not dependent on the sum of the parts, but the balence between them, limited by the weakest link.
Can I suggest if you want to do this properly, you shoot a test image on film, then shoot the same image on a digital camera.
Can I suggest that that is the right answer to another question?
Its the 'real world' answer to test which delivers better 'image quality'. On Bag, everything thrown into the pot, especially if you add..
Also... scan it... as that is the only real way film images will be disseminated in the real world
Bringing us to a point of probable agreement.... 'in the real world' displayed on a 1080ish pixel screen.... any resolution above that is probably redundant ANYWAY. Any detail that cant be cought around 1.3Mpix is unlikely to be seen by very many people.
The OP's question, was; "What do you consider 'High Res'?" and I answered "Film"
You asked me to explain and support my opinion that the 'resolution' of 35mm film was around 100Mpix equivilent, and do it with 'real world' explanation.
I have done that; I have shown the empirical evidence I looked at; 24Mpix scan of full frame image... pixilating out, at high magnification, where higher Mpix scan, up around 100Mpix I could still see detail not captured at 24Mpix.
And now you are challenging me to ultimate IQ tests comparing film to digital?
OP's intent might have been to ascertain what 'resolution' people felt gave better image quality, or what was an adequete sensor resolution, but question asked wasn't about image quality, but simple detail resolution.