IMO that 3rd target will vary on the D and on the circumstances. It seems to me that McVay's concept is to scheme up the toughest match-up for the D that they are playing. So, it's not just routes run according to the position a player plays (RB, TE, Slot, WR), but rather whatever routes work best against any given D. The Rams are building flebility to use players to run non-traditional routes for their position. They've been using WRs as TEs for some time. Now, they are looking to use TEs as slots, even WRs.
Bottom line: After WRs' 1 and 2, there will be no clear #3 and that is on purpose.
