I was trying to think of who would be a comparable pitcher to Nola who was traded at roughly the same point is his career. The best I could think of is Chris Sale. Sale was 27 when the White Sox traded him, same age as Nola. Sale had two plus good years (15 WAR) for the Red Sox before getting a big contract and then getting hurt. The White Sox got one useful player in the trade, Yoan Moncada. After two mediocre years, Moncada had a 5 WAR season in 2019 before regressing this year (though I wouldn't draw any conclusions from anyone's 2020 performance). I'm on the fence as to whether I would trade Nola for the equivalent of 2017 Moncada.
Another comparable is David Price, who was 28 when the Rays traded him for three players who all have played in the majors for several years. Nick Franklin was a bust, and old friend Drew Smyly, who pitched well for about a year until he got hurt. The best turned out to be Willy Adames, who was 18 at the time and is now the Rays shortstop. He's a 5 WAR player at age 25. I think I would be OK with a haul like that for Nola.
The next match I came up with was Johnny Cueto, who was a little older when the Reds traded him for three pitcher in their early 20s. The best was Brandon Finnegan. I don't think anyone would trade Nola for that kind of return. Cueto may not have been quite as good as Nola, though.
I couldn't find any more recent comparables. The Padres traded Jake Peavy back in 2009 when he was 28; the return was pretty much Clayton Richard. Pass. (The return for the 33 year-old Peavy was then 25 year-old Heath Hembree.)
It seems like the Phillies might get a good player back for Nola, or they might not. There is of course the saved money to consider.