If Kante and Jorginho go, there might be room in their midfield. Although it makes a mockery of Lampard talking up RLC and Mount.
On the other hand, Havertz is on another level of talent than RLC and Mount. RLC being a CM anyway. Havertz can also play 10, 10/8, right wing and false 9, wouldn't mean either RLC or Mount would be completely sidelined. And if you actually have the chance of getting a talent of Havertz's level, you try.
Got a similar discussion at Stuttgart right now. We've got two great talents for SS/AM in Egloff and Klimowicz, but are apparently interested in this 17 year old guy Demir from Rapid Wien, who's supposed to be a generational talent. Some say you kill those already at the club by signing him, others say if you can get someone like that you do.