Looking at the stats, 28 appearances in all competitions this season for Eriksen compared to Lallana's 30 but Eriksen played 1,428 minutes and was involved in four goals whereas Lallana managed only 951 minutes and notched just the one assist.
The problem with signing an experienced striker is who makes way? We have Welbz, Fergie, Pedro, and potentially also Undav competing for the CF role -- and that's excluding O'Mahony who I expect will go out on loan.
Otherwise, and putting aside the question of how big a salary we would have to...