Maybe independent candidates will join PTI, because PTI winning 137 seats to form an independent government isn't going to happen. What is your guess about next government?
That will depend upon on whether those independents join the PTI party, like what they did in 2013 when they joined with PMLN or they form a Jeep kind of group and then join the government as a coalition partner.
PTI is sure to form a government in KPK, and with pending KPK-FATA merger many of the 12 FATA members will prefer to join PTI and to get some influence in the provincial assembly as well.
So if PTI gets to a 100 seats somehow, then say get 10 out of 12 Fata members, taking their tally to 110. Then they will be just 27 short and in this case many independents will find it beneficial to join the PTI party, say they get 15 independents. Taking their total to 125, in this case BAP, PSP and GDA(PML-F) can come together and join PTI's coalition. Now all three of these parties are pro-establishment, so military will have a lot of influence in the government. And with both PMLN and PPP sitting in opposition, life won't be easy for the PTI in the center.
Now if PTI gets less than what is expected of them, any thing below 90 will mean they will never form the government even if they are the single largest party. The only option will be to join PPP which will be a political suicide.
Let's say PTI gets 90, PMLN 70 and PPP 40. With MMA getting around 10. PKMAP might get a couple of seats. In this scenario, PMLN-PPP-MMA-PKMAP can form a coalition government with the help of 15 independents. Such a government will be very weak and won't last for long. We might end up with another election being called a couple of years down the road. In such a government the biggest loser will be PMLN, as any alliance with PPP will result in serious vote bank loss. So in the next election PTI can actually perform much better in Punjab.
PTI will already have around 30 seats in its bag when it enters Punjab (20-25 KPK, 2-3 ICT, 2-3 Sindh(Karachi) ) but it will require 70 out of 141 Punjab seats to get into position of forming a government.
It is tough to say if it can get there. They surely dominate northern and southern Punjab, but major chunk of seats is in the central Punjab.
North has around 15 seats (they can get around 8 seats(3 Attock, 3 Rawalpindi, 1 Chakwal, 1 Jehlum) + 1 for PMLQ's Pervaiz elahi in Chakwal), South has 46 seats and with the inclusion of some heavy weights they can get around 25-30 there. So in best case scenario they will have around 38 seats from north and south, but they will still need 32 seats out of 80 central Punjab seats which I feel is difficult to achieve.
They have made inroads but would that be enough. Take Lahore for example, out of 14 available seats PTI got just 1 in 2013, this time they are expected to get 4 there. That will mean them requiring 28 more seats out of the remaining 66.