Lebron makes any team incredibly dangerous on offence but that team has very real defensive issues that I don't see just magically getting better. Its one thing to not be trying but even with full effort they aren't even going to be average.
Key for Raptors will be can the young players step up and knock down open shots. Delon, FVV and OG are going to get a ton of open looks with teams focuses on Derozan/Lowry. If they can knock down 3s the Raptors should be fine, if they don't there could be a few issues.