Anything that is actually implemented and deployed is by definition legacy. Googling for "legacy Java code" (exact phrase) today produced 444 hits, "legacy Java" by itself almost 30,000, and even "legacy XML" 619.
As usual, Frederick Brooks called it correctly thirty years ago in The Mythical Man-Month, chapter 1
[T]he product over which one has labored so long appears to be obsolete upon (or before) completion. Already colleagues and competitors are in hot pursuit of new and better ideas. Already the displacement of one's thought-child is not only conceived, but scheduled. [...] As soon as one freezes a design, it becomes obsolete in terms of its concepts.
Of course, he also says, with understatement that is less than usual in our profession:
The new and better product is generally not available when one completes his own: it is only talked about [...]. The real tiger is never a match for the paper one, unless actual use is wanted. Then the virtues of reality have a satisfaction all their own.