He's had some niggles for Southampton but since leaving Liverpool he's played as much as Kane. I'm pretty sure he's soon out of contract too so unless he signs a new contract, he won't cost anything like as much as they would have otherwise asked for. Personally I'd take him all day long for the right price. He's a proven Premier League goalscorer at the end of the day, and has a great attitude. The likes of Edouard and Daka that have been mentioned are only proven yet in really poor leagues. (Scotland and Austria)
If he is coming in around 20m I would take him as well. but I think he is going to be a ridiculous price like 40m+.
I think we need to look beyond next year if Kane is leaving and Ings beyond next season looks like a terrible option. Yes his knees have been fine since coming to Southampton but do you want to bet on those knees holding up as he gets into his 30's?
If we are looking at someone like Ings, I would rather spend more to get a guy like DCL that has the same proven PL experience but will be good for more than 2-3 years or a more talented guy without PL experience who again would be here longer than 2-3 years.
Ings seems like the typical band-aid solution signing that we need to replace almost immediately after signing that were terrible previously, but at least made some sense when trying to maximize results with Kane here, but now that it looks like top 4 is gone for next year I prefer to bring in guys that can get us back to top 4 not hopefully get us to squeak into 6th.