My hopes:
Rocky Mountain Construction coaster
Winged coaster
Eurofighter coaster
Spinning coaster-Gertlauer
More realistic Peeps
In-game aged footers and realistic supports
More realism in stalls and facilities
and a lot more Trees!

I would want less lag, more coaster customization, better graphics (especially the peeps), ride gift shop customization thingies xD, better sounds, the RCT4 video camera to be much less slow, more realistic Career Mode parks, better terraforming ways, and maybe more realistic trees with better graphics without the weird martin plants.

RCT4 has been unoficially renamed to NL2.

Just puttin' that out there.

RCT4 has been unoficially renamed to NL2.

Just puttin' that out there.

Actually I think Theme Park Studio would be its closer relative.

ThemePark Studio!? I’d forgotten all about that.

I’m sure the almost-rans and the has-beens all wannabe but RCT4 has yet to make an appearance. Mavens and aficionados of the series will know 4 when it arrives – no pretence will be required.