IMO, yes - and I'm saying that in terms of what our ultimate aim should be. If someone's expectation is for United to maybe compete for the league, then that target of ~20 goals per season might be reasonable. But if it's to be genuine European heavyweights, I think we should look at better options (either now, or in a couple seasons) - because these days, the elite clubs (those that regularly reach the semi-finals of the European Cup) have #9s who're scoring close to 40 goals per season, apart from being great off the ball, and in terms of technique as the fulcrum of the attack - who piece the whole thing together, and make it greater than the sum of parts. And with that in mind, €60m should fetch us someone who can potentially be the best at his position - like Suárez or Lewandowski are, and I don't quite see Lukaku emulating that (could be wrong, of course).
There is however a player currently at the club who can reach that standard in the not too distant future, and having Lukaku as the de facto #9 might jeopardize his transition from a left inside forward (his best position right now) to a devastating #9 (his best position in terms of development). Because the way football is headed, you have superclubs stacked with world class players at almost every position (unlike the past where the distribution of quality was more equitable between United, Juventus, Milan, Bayern, Madrid among others), and to keep up with said clubs (United have fallen by the wayside in recent seasons, that much is undeniable) - we should either aim for the very top bracket of players, or youngsters who can reach the level (like Martial). The process might take a couple seasons, or maybe even more - but that's what it is going to take to reinstate the club to its mid to late 2000s standard.