So, Pollard would not have to have been changed with treason to be subject to death, or have the sentences changed since then?
Apparently the deal is that after the death penalty was revived in the late 1970s, espionage convictions weren't just automtically subject to it in the way they'd been before. I found something showing James Trafficant trying to get it passed in 1989--probably in the wake of Pollard. It's definitely on the table today--here's the DOJ worksheet to decide.
Of course, the other problem with a treason charge is that what it is is very explicitly spelled out in the Constitution."Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court." Did Pollard levy war against the US? Is Israel our enemy? The latter, at least, is a question that I can't see any administration wanting to get into.