Yes, they should have built T4 on the north side by demolishing something else? Is there any space left (I daren't say why not convert Waterside!). Or perhaps moving out some of the vast maintenance hangers and building a terminal between 27L and 27R.
Failing that, I'll stir the pot good and proper by suggesting building the 3rd runway south of T4. Fill in a few reservoirs and we could have our very own "Stainesbaan" to rival Schipol.
Sorry - feeling a bit mischievous today.