[godelski]

  > might surprise burn your tongue half an hour later.

A *good* vacuum-insulated bottle should be able to do this 90 minutes later. I have some non expensive ones that will keep my tea hot for over 10hrs. Not warm, I mean hot. Even a cheap $10 thermos brand thermos will do at least 6 hrs. They even frequently have cups as caps. I'm sensitive to heat and always need 5 minutes after pouring it into the cup, hours after making my tea.

We're so good at keeping liquids hot it's crazy. If you can't either drink your liquid in 10 hrs or get to a microwave within that time, you're looking for a pretty niche product and a self heating bottle isn't it.