I’d actually prefer if they don’t add planes or ships. I don’t see how they would be realistic on such small maps. Ships are way too slow and big and planes are way too fast and I think it’d ruin the experience.
I don’t mind airports or harbours to make a new sort of industry, I think that’s a great idea actually. I’d love to see a harbour with goods that are ”Imported Goods” or something and airports to which a large number of people want to go to, but I think it’d be a bit ridiculous to have a plane fly just 16 KMs to another town at 500 MPH or to have a gigantic ocean liner on a tiny canal.
Not to mention that you’d have to build a canal to be able to use boats properly, which is hugly inefficient compared to rail- or roadtransport
So I’d actually say, don’t bother with planes or ships…