Slightly off-topic and slightly tongue-in-cheek (but only 'slightly') here...
All this talk about 1st, 2nd, 3rd and 4th choice strikers has got me confused: I'll readily admit to that. So just to try to clarify where I am with my take on it...
In the season just gone we played a couple of attacking formations: three at the front and two at the front.
When we played with two the "1st choice strikers" were Suarez and Sturridge. When we played with three the "1st choice strikers" were Suarez, Sturridge and Sterling.
Therefore; when we played with a two [Suarez and Sturridge] it follows that Sterling became the "2nd choice striker" if either were injured/subbed... with Raheem moving up front.
If we played with a three [Suarez, Sturridge and Sterling] the fact is our "2nd choice striker", if either were subbed, was either Aspas or Moses.
Our "2nd choice strikers". However, more often than not, when either were called on, Brendan reverted to a two. Why? Well, in my opinion, that was because neither were good enough to be "2nd choice striker".
If we, finally, land that quality wide attacker/striker Brendan has been seeking, the chances are he'll play in a mobile, interchangeable front three. Or, if you prefer, he too will be a "1st choice striker".
If that is how things pan out then "2nd choice" cover, for a front three, will come from Sterling, Coutinho and a.n. other [Borini?]: with either Sterling or Coutinho being moved up front from midfield and the other occupying the role left by the other. Or Borini used as a direct replacement - the choice is Brendan's.
So by my reckoning if Borini stays and if we sign that quality forward then he will, in effect, be a
"2nd choice striker". Simples.