This rumor is about a day old, which makes it ancient history in Internet terms. It's also of the kind that contains phrases like "Sportsmail understands...". But here's it anyway, since it's a thing that people talk about, have talked bout, will talk about.
Chelsea being linked with the 28-year-old Gonzalo Higuain is nothing new of course; it's been happening with regularity over the past few years. Even though we've lost our connection to the former Real Madrid player when Jose Mourinho was sacked, Antonio Conte wears the Serie A's stamp of approval and thus apparently could also be tempting for the Napoli striker. Tempting enough, at least according to the Daily Mail, to forgo Champions League football with Napoli, in fact.
Spending £42m on a position where we already have a clear cut starter and several backups is a bit silly, which is perhaps why the Mail also claims that the only way Higuain would agree to a move is if Diego Costa moved on as well (to China, or back to Atlético). And since neither of those is looking all that likely at the moment, Higuain shouldn't really be considered a serious transfer target at this point.