A person can only deduct debt/expenses already incurred. As for future expenses, those cannot be deducted. Consequently, cash earmarked for those future expenses, such as savings for Hajj or Umrah, would be treated like all other cash and would be therefore be zakatable. A simple way to look at it is: how long we live is unknown. When calculating zakat today, we only deduct what would be outstanding if we were to die today. As for future expenses, we might not live long enough to even incur those expenses. Therefore, they would not be considered when calculating zakat. And Allah knows best.