Good partnerships can continue.

How will they be next season?

They'll lose a star, but that doesn't necessarily mean they'll play worse. My players tend to have better form, the longer I keep them on my roster (granted, I usually maintain the quality of good performers).

How strong is your league? If it consists of many solid squads, the more confident i'd be in them playing well next season. If your league has like only 3 active/semi-active managers, then getting atop the goals/assists/ratings table, then it'll be additionally wise to take those stats with a grain of salt, due to lack of quality competition.

Just wondering if I can invest money and tokens elsewhere?

I'd still be targeting a striker. Since TE players retire young (32-34 yrs old), I'd get in front of the problem and acquire a ST (preferably a nordgen), once the transfer market dies down. However, if other positions are more pressing, then target those needs first.