Metallica released Garage Inc. in 1998. The compilation was one disc of newly-recorded cover songs and one disc of previously recorded cover songs (including their 1987 covers EP The $5.98 EP – Garage Days Re-Revisited). Now according to Kerrang!, drummer Lars Ulrich didn't exactly say no when asked about if there will ever be a Garage Inc. 2.
Aran from Leicester asked Lars if Metallica were going to make Garage Inc. 2, which songs would they cover? To which the drummer replied “Wait and see…”
Since then, Metallica has recorded covers of songs like "When A Blind Man Cries" by Deep Purple, "Remember Tomorrow" by Iron Maiden, and a medley of Ronnie James Dio's career under the title "Ronnie Rising Medley", and "So What?" by Anti-Nowhere League. So who knows what they've got planned in terms of either including those or just recording a whole new batch, if this even happens.