Putting money on it now- D/P remakes are coming to Gen 7. Of course, that brings up Shocari's point of how previous remaked games were on obsolete consoles and thus needed to be modernized. Well, perhaps this is the time for a new console?
The original Nintendo DS was released in North America in 2004. Several different versions were released including a version that no longer has backward compatibility to old GBA games- the DSi, which was released in 2008, making the GBA finally completely obsolete. The DS lasted four years. The 3DS, which introduced all new 3D graphics to the sixth generation, was released in 2011. Maybe, just maybe, Nintendo is planning a new 3DS that will make the DS become obsolete (Probably called the 3DSi), giving Nintendo a reason to remake Diamond and Pearl.
And hell, maybe it will be a little later than seventh gen. Perhaps this will be as far back as gen eight. But mark my words, the 3DS and it's backwards compatibility will come to an end.