As of now Sri Lanka Premier League have got 7 teams. Bangladesh Premier League have got 7 teams. Afghanistan Premier League have got 5 teams and Everest Premier League have got 8 teams. Among this same player will be playing different leagues for different teams. Only in such occasion there arises problem.
Having teams from Oman, UAE and Saudi Arab is also not ideal situation for them because most these countries not have native players so in case of they will have few matches in these countries will be also good but having more teams will never been ideal.
PCB cannot afford to increase the duration of the tournament as players have also domestic and international commitments and they cannot spend all the time in these tournaments. Also if there is a conflict in date in the PSL and IPL, many international players will prefer to play in IPL as compared to PSL and for sure PCB won't want this to happen.
One suggestion is to increase the number of teams in PSL but schedule more than one match in a day at different venues. This may achieve the purpose of increasing the teams in PSL yet the duration of the tournament will remain the same.