I don't see why you lot are being so pessimistic and cynical about established political leaders joining the PTI.
A few things to keep in mind here:
1. Some of these politicians have declared an intent to join the PTI, the PTI has not yet issued tickets to these politicians to run in various constituencies
2. Some of these politicians do not want to joint the PTI, but are willing to cooperate with it and support it as part of a coalition perhaps - again, the PTI has not officially agreed to any formal coalition or adjustment of seats
3. 'Same old politicians' is not enough to criticize the majority of the individuals seeking to join/ally with the PTI - unless critics can show how these politicians tangible engaged in corruption and/or mismanagement while in positions of leadership (as governor, Prime Minister, Minister of XYZ etc.) criticizm should be reserved.
There are politicians in the existing PML-N, PPP, MQM parties who are honest and might do well if given a chance at leadership, but they have not had a chance because of the Zardari/Bhutto/Sharif/Altaf dictatorships in these parties. Imran Khan and the PTI may also go in that direction, but until we try him and give his party a chance to establish itself, we will not know whether he will turn out to be the same kind of politician as the current lot.
The Bhutto's, Zardari's, Sharif's and Altaf Hussain's have been given enough chances, and they have failed. Time to try someone new, and that someone is Imran Khan.