Now that Houdini VEX supports dict type in 18.5, will it support multi-dimensional arrays in Houdini 19? I've been waiting for this for many years...

Nobody will be able to give you an answer.

If you would like this feature let SideFX know in a way they can track it, feel free to submit an RFE here [www.sidefx.com].

houdini 19 difficult labour

Would be cool, but you can just use flat 1D arrays and write a simple 2D/3D --> 1D indexing function to map the index to the flat array. This is done in a lot of libraries / codebases as it reduces the number of indirections needed when accessing the internal elements of the nD array.

Eg, map a 2D Index to a 1D flat array use : i * N + j.