A wall along the entire US-Mexico border will never be built, no matter how the current budget standoff and shutdown gets resolved. The $5.7 billion the President is demanding is only a down payment. The Trump administration has claimed the entire thing will cost $21.6 billion, however that number is widely viewed to be too low and Congressional Democrats have claimed when they run the numbers their estimate is around $70 billion. Either way, the total cost will be many times more than the $5.7 billion that Trump is having so much trouble getting right now.
Plus, this would be a really big project that would take years to complete and would require a sustained funding stream to keep it going. The Democratic majority in the House is solidly against the wall, which means such a funding stream will be very hard, if not impossible, to get in the next two years. But even after two years, that opinion among Congressional Democrats is unlikely to change because the American public is against building a wall and overwhelmingly does not believe building it should be a priority.
Even if Democrats back down and give the President $5.7 billion for a wall right now, the wall still won't be built. The politics are too toxic to sustain a project that big for that long. What the Republicans are demanding now is not an actual wall, but the opportunity to burn $5.7 billion so Trump can think he "won." That is all this is about.
