Lautaro himself reportedly wants to come, but Inter will ask for a hefty fee plus at least one player in exchange. Barcelona may be unable to meet the demands.
If the deal falls through, as the Neymar deal fell through last summer, then Barcelona will opt for Werner. The main problem is a lot of teams are in for him, most notably Liverpool. And the player himself has expressed interest in playing in England.
After signing Lautaro, Werner, or another superstar forward, Barcelona may be done spending money. Instead, they will rely on player swap deals to shake up the team.