Re: How many Shuttles could have been kept operative..
yeah about Mexico paying for the wall - indirectly, it's already started. The current 'NAFTA replacement' agreement is supposed to be a part of that. Additionally, there's a new agreement with Mexico that asylum seekers (the ones that go to the border to make their claims) must WAIT IN MEXICO for their trial dates, and NOT cross the border and 'become lost' inside the USA.
Of course, more fixing needs to be done, but there are direct payments and "cost savings to the USA" payments that are involved in 'Mexico will pay for it'. Ultimately I think Mexico may actually come out ahead in 'paying' for the wall. Imagine what would happen to Mexican law enforcement costs if the DRUG CARTELS and HUMAN TRAFFICKING "industries" were SEVERELY curtailed because of a wall... and the cost to MEXICO for law enforcement would go down, because organized crime would NO LONGER BE ENABLED by "stupidity" laws that hamper border enforcement and literally turn the USA into a MAGNET for illegal border crossings.
Yeah. 'Everybody wins'. That's part of the 'art of the deal' I think.