Does GDI have the same long term support as DirectX and Direct2D?

We are at the beginning stages of of a major redevelopment cycle for software that has a lot of GDI code for rendering (think along the lines of a GIS application) written in C# with some back-end C++ code. For this next cycle we are expecting to have a product lifespan of at least five years, possibly as much as ten. The plan is to support Windows 7, 8, 8.1, 10 and so forth with a fairly good chance of also providing support for tablets and mobile devices.

As such, one of the things that we are investigating is if we should take the time to move from GDI to another technology such as Direct2D. One of the major questions driving the business right now is if GDI will have strong long term support and the capability to support those platforms over Direct2D. Since there seem to be a lot of broken links in articles, done anyone know if Microsoft has released any road maps or similar documentation that might prove useful?