From Longman Dictionary of Contemporary Englishjam tomorrowjam tomorrowBritish English informalPROMISE good things someone promises you, which never happen There is an element of ‘jam tomorrow’ about some of the government’s policies. → jam
Examples from the Corpus
jam tomorrow• If not culture jam today, then certainly culture jam tomorrow.• Will it really be no jams tomorrow?• Not for him the promise of jam tomorrow or a brave, new world waiting just around the next bank overdraft.• Jam yesterday, jam tomorrow but never jam today. 