In Group A, Australia, New Zealand, and Sri Lanka have have made it through to the quarterfinals. Its only Pakistan that has an outside chance of really screwing up and missing out.
Lets take a look at some of the scenarios.
Optimistic Scenario: Pakistan wins both its matches against Zimbabwe and Australia
If Pakistan does manage to win both these games then it will top Group A if Sri Lanka beat New Zealand. However, if New Zealand beats Sri Lanka, then both Pakistan and New Zealand will be on level points and Pakistan will probably be second in the Group due to New Zealand's better net run rate.
Realistic Scenario: Pakistan beats Zimbabwe, and loses to Australia
In this case Pakistan will either be third in Group A or fourth. If Sri Lanka beat New Zealand then both Pakistan and New Zealand will be on level points, but most likely New Zealand's better run rate will mean Pakistan end fourth. However, if New Zealand beat Sri Lanka then Pakistan will end up as third in the Group.
The same will be the case in the rather unrealistic scenario of Pakistan losing to Zimbabwe, and beating Australia. Actually, knowing Pakistan that's not unrealistic at all! In fact I may even place my bets on this happening.
Pessimistic Scenario: Pakistan loses to both Australia and Zimbabwe
This might lead to a tricky situation if Zimbabwe beat Kenya, because then Pakistan and Zimbabwe will be level on 6 points each and net run rate will decide on which of the two qualify as fourth in Group A.
As of now, Pakistan's net run rate is superior, but that could change based on how heavy Pakistan's two losses are and how big Zimbabwe's two wins are.
So there is still a chance, albeit a very small one, that Pakistan does not make it to the quarterfinals. Unlikely though.
So no real surprises that even at this stage and despite looking like topping Group A one week ago, Pakistan can still end up in any position from 1st to 4th to even knocked out, at the conclusion of the group stages!