SAM 28000 and sister ship 29000 are getting a little long in the tooth but even if the order is finalized today it will be years before a replacement arrives.
Both are getting major avionics upgrades starting this fiscal year (after many years of planning / R&D) since the replacements aren't expected until 2024.
By the way, each full turn in that holding pattern cost taxpayers about $15,000 USD in operating costs.
