Well, let's see the sequel, it seems need more information.
.......
Parameters are:
8MB cap
Doubling every two years (so 16MB in 2018)
For twenty years
....
Does that mean in 20 years after it starts doubling the blocks will be 8192 MB, which is 8.192 GB per block?
Have I done my maths right?
8 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 8192
To keep it simple I'm not considering the difference between mebibytes and megabytes.
What? that's too much right

He told doubling every 2 years, so every 2 years increased 8MB. The parameters will implement next years(2016) and then in 2018 increase 8MB, so 8+8=16MB.
You means 20 years after starts. Start from 2016 and the end is 2036.
8MB(2016) + 8MB = 16MB(2018) + 8MB = 24MB(2020) + 8MB = 32MB(2022) + 8MB = 40MB(2024) + 8MB = 48MB(2026) + 8MB = 56MB(2028) + 8MB = 64MB(2030) + 8MB = 72MB(2032) + 8MB = 80MB(2034) +8MB =
88MB in 2036.CMIIW.
~ikiNo, the 8102MB are correct. You only summarized 8MB each 2 years, you need to double the max blocksize of the previous year.
Though 8.1GB per block, so each minute, sound extreme. Ok, 20 years in the future is a long way but still. I wonder how harddiscspace will develop till then. Or whatever we will use to write data on then.