The comic is still accurate and always will be. It's just a mathematical law, even though it uses a popular display of it.
What you are wondering about is the size of base of the exponentiation. Let's look into that.
If you use individual, unrelated letters, this is 26 (or 52 when you allow uppercase, or 62 if you also allow numbers). At e.g. 12 letter, this is 62 to the power of 12. At 16 letters, it is 62 to the 16.
If you use words (as the comic proposes), then the dictionary size will be the base (in this case, 4000 or so). You have fewer words, so entropy is 4000 to the 4.
If you use phonologically grouped words or syllables, the base size is their number. I'm not a linguist, but I'd guess it is somewhere around 100 or so. If a syllable is 2 to 3 letters long and you use 32 letters, you get something like 12 syllables. Entropy is 100 to the 12.