Nokia please bring back "E90 Communicator", in today's smartphone world the communicator can play an crutial role which will be a compact laptop too. You can try this with midrange phone like Nokia 4/5 which will be on huge demand.
For compact you can make Query keypad/keyboard slim so it will be compact and can be kept on pocket. For that you can make screen/keypad rotatable to 180 degree like classic E90.
Also it will be best if you make a dedicated OS(Maemo/Sailfish OS) for it to make the phone totally standout from others brand or for timebeing Android will also fine.
Yes, I also loved the phone model Nokia E90 Comunicator because it was the first 2in1 mini laptop and it was very useful. Now I'm thinking seriously to buy again this phone since I found new one for sale the only disadvantage is the poor performance (CPU:330Mhz and int. mem.: 128Mb) compared with the present phones on the market. The ideea to make a newer model after the E90 Comunicator it's not a bad ideea when now there are new technology to implement in the new E90 and make it better than his predecesor. Don't forget that the E90 Comunicator was the best phone sold at that time and is still is.
Another request for a smartphone with full keyboard! Personally I'd prefer a slide out keyboard like the N950 but foldout with a T9 layout on the front would be fine :D