There is a simple explanation for why tactical nukes will never be used. The nuclear exchange may or may not escalate. If it does escalate, are the consequences acceptable to Pakistan? Is national pride more important than the nation?1. If India made a limited break in Punjab or Sindh, attacking Indian airfields, assembly areas, and div and corps level HQs would be an unacceptable escalation. Hitting Indian troops within Pak. territory would not.
5. Tactical nuclear weapons are not for threatening only (like strategic weapons are), they are meant to be used. If Indian troops make significant breaks in LOC, tactical nuclear weapons can be used to remove them.
India will not attempt to annex Pakistan. It is simply not possible. It might opt to conduct salami strikes to capture ground that can be used as a bargaining chip later. Nothing more. The Pakistani leadership knows that very well. Once, nukes are used all bets are off. Neither country has a defined nuclear policy.