Yeah it's a bit of a tricky situation, but whatever front 3 we go for long term, I would bet Rashford and Greenwood are both in there. Could be all 3 of Greenwood, Rashford, Martial, could be Sancho in for one of them if we manage to bring him in this summer or next summer, but we'll see. It's not perfect but I would be pretty OK with not signing an attacker this summer (past James). We need to revamp our midfield and defence. If we bring in 4 quality players there (something like Rice, Tielemans, Cancelo, Koulibaly), then our attack will be way better as a result.
Look at Liverpool. Alexander Arnold got 12 assists in the league alone, Robertson got 11. Shaw has like less than 5 in his career, whereas our right back (right flank really) is entirely non existent. We fix our back 4 and midfield on both sides of the ball, and I think the likes of Pogba, Martial, Rashford will show more consistency. If not, we focus on the attackers in summer 2020 anyway.