Transpire has two related meanings. The second was once beloved of pedants who argued against the first, but the first has a long history of use (see below*):
- to happen
“No one is willing to predict what may transpire at the peace conference.”
- If it transpires that something has happened, this previously secret or unknown fact becomes known
In either sense, a thing may transpire in the future, and there seems no reason to restrict its use to the present. A present secret may transpire (become known, be revealed) in the future. A thing may transpire (happen) in the future.
*Here is Merriam Webster on the verb:
Sense 1 : to take place : GO ON, OCCUR
Sense 2a : to become known or apparent : DEVELOP
Sense 2b : to be revealed : come to light
Can transpire mean 'to occur'?:
Sense 1 of transpire is the frequent whipping boy of those who suppose sense 2 to be the only meaning of the word. Sense 1 appears to have developed in the late 18th century; it was well enough known to have been used by Abigail Adams in a letter to her husband in 1775. there is nothing new transpired since I wrote you last — Abigail Adams Noah Webster recognized the new sense in his dictionary of 1828. Transpire was evidently a popular word with 19th century journalists; sense 1 turns up in such pretentiously worded statements as "The police drill will transpire under shelter to-day in consequence of the moist atmosphere prevailing." Around 1870 the sense began to be attacked as a misuse on the grounds of etymology, and modern critics echo the damnation of 1870. Sense 1 has been in existence for about two centuries; it is firmly established as standard; it occurs now primarily in serious prose, not the ostentatiously flamboyant prose typical of 19th century journalism.