To answer the question what does one need for a large setup, it is basically maxed out RAM, as many multicores as possible, samples stored on SSD and probably separate slave(s) for playback so that a single computer doesn't have to handle both DAW and sample playback.
Nevertheless it makes no sense to use that many channels or ports. This is a large orchestra with full instrumentation:
Piccolo
2 Flutes
2 Oboes
English Horn
2 Clarinets
Bass Clarinet
2 Bassoons
Contrabassoon
3 or 4 trumpets
4 (or 8 horns in the largest orchestrations such as Mahler and Strauss)
2 Tenor Trombones
Bass Trombone
Tuba
Timpani
3 to 4 percussion
Harp
Pipe organ
Piano
Strings divided into 5 staves.
Using Vienna Instruments and Vienna Ensemble one can have on EACH OF THESE TRACKS dozens and dozens of different artiulcations using the different samples created by VSL which fully represent the most complex orchestration.
This means that a huge symphony orchestra of the type listed above will be totally represented by 37 channels - meaning three ports with some channels left over. This orchestra is totally sufficient within the constraints of digital sampling for any composer for television or film. In fact it can credbily represent far more complex concert music. The simplest music of all is Hans Zimmer's massively layered block chord composing with percussion noodling. There is zero complexity to that music, and most film and TV scoring is using that simplistic formula today.
And you ask what would Wagner have used? Something smaller than Mahler or Strauss who went beyond him in size and complexity of orchestras. Mahller added a number of extra instruments - such as the 2nd Symphony's use of E flat soprano clarinet, extra brass choir, etc. But even that gigantic symphony which dwarfs TV and film music in complexity only uses a few more diffeernt instruments. Strauss's Alpensinfonie or Also Sprach Zarathustra tone poems use giant orchestras as well - but all of these are completely representable with 3 or 4 ports with 48 channels to 60 channels.
If you wanted to included multiple layered performances in the strings - such as using Dimension Strings, this could concievably increase the number of channels by 24 if you put each instrument on a separate channel which is generally not needed. Most people will use all 8 Dimension Violins - or may be two sets of 4 - for example on one or two channels and use separate humanize settings within each instrument.
My Romantic Symphony which you will find HERE uses for the entire performance a total of 85 tracks including Appassionata Strings, Orchestral Strings, Chamber and Solo along with all the Dimension Strings, complements of 9 woodwinds and 15 brass, 6 percussion, harp and pipe organ. But all those instruments easily fit on only 3 ports using 48 channels.