Aren't the platforms essentially the same as they were in the Pennsylvania RR days? I mean, aren't they the same width and length? If so, then yes, refurbishing the concourse would be a huge improvement to the Penn Station experience. With new tunnel proposals, I haven't seen any indication of widening the platforms.
Just out of curiosity, can they dig new tunnels under the existing ones with a new set of platforms 25-50 feet below the existing ones? That's the ONLY way I see relief on the platforms and perhaps maintaining or increasing capacity.
Tokyo station isn't really that much different, style wise, on the platforms. It's a huge gated station with additional gates to Shinkansen. But once through the ticket wickets, there are hundreds of thousands of square feet of retail, stairs, platforms, moving sidewalks, customer service, etc. The main station is at ground level and there are 10 platforms with 20 tracks above 2 stories higher. There are also two separate areas with two platforms and four stubs each 4 stories underground. When I was in high school, I had to walk between almost the furthest two points in the station. Tokyo Station has around 450,000 boardings daily. Doesn't include through traffic. So, not much unlike Penn Station.
I say that to say this: they literally raised two or three platforms and associated tracks in the 90's without disrupting service. When there is a will, there is funding. When there is funding, there is a way. Chronic problem in New York seems to be overruns every time a project starts. I'm not going to claim corruption, but there's a HUGE difference in how money is spent when the Government provides funding vs when a private enterprise spends theirs.