I agree the trade was worth making on its own terms, but that's where the Phillies' failure to double down on the JT/Cutch/Segura core by paying the tax for at least one year, if not two, is a big failing.
I also separate it at least in part from whether it made JT more likely to re-sign. The Phillies have already failed to capitalize on most of the advantage they had with him being "in hand," whether due to their own thrift (not willing to meet his arbitration number, not willing to pay the tax) or JT's preference to test the open market. In the end, if we don't sign him until it's an open market and we're high bidder, we'll have had no edge. If he signs early or takes a bit less to be here, it counts.
Of course you also have to include the draft pick in the equation and that could still end up being worth as much as Alfaro (but only if it is used well).
It was fairly similar to the Lee trade. If Sanchez ends up being Carrasco that is fine. If he blows out his arm that will be sad, but would also highlight the fact that you never know with pitchers.
What JT does instead of Sixto in the future doesn't really affect the trade either, though it (and Crawford) will be a referendum on the fact that the Phillies failed to win anything before the cupboard was bare. If, in fact, that's how it plays out.