Liverpool still have no striker signing on their agenda currently. However Firmino's absence must push them to look for a replacement. They can't move on to the next season with only one striker in the end. Nunez's possible injury can cause us to see Gakpo as a centre-forward again. This wouldn't be much ideal for Liverpool at all.
If they don't want to spend so much money on a striker than they can look for a loan option or a favorable low-cost striker as a subtitute of Nunez. Nunez will also need to make some good improvement this season to prove his skills to Liverpool as well.