Well, we're not there now, so the best we can do is do what we can do now, and promise ourselves to do what we can then. Maybe we will, maybe we'll fail, but there's literally nothing we can do about that now, so why let cynicism about a potential future erode our resolve to do what is right now?
You should care, as should anyone who is aligned with these protestors' views. That's because if (or when, if history is a guide) the protests subside because "we elected not-Trump/Democrat-X/whatever", the gains will be eroded or erased as Trump's policies are continued by the new "savior."