To be this is not a good idea at all:
(1) Our recent past tells us about many fraud schemes started like this one but never completed. Purpose is just collect money.
(2) We are going to ruin the environment if we go for it, a very serious crime
(3) No more natural beauty for which the Capital is know for. No more "Islamabad the Beautiful"
(4) New cities ore need of today but never build those adjacent to each other. There should be distance of at least 50 KM from each other
(5) New Islamabad (if they are really serious), should be built 50 KM away from the current city boundaries e.g. On motorway somewhere between Chakwal and Talagang or somewhere after Fateh Jang
(6) Then existing city boundaries should be locked, no more housing schemes after the boundary