Been reading lately that there has been a SHA1 collision found by researchers sometime last year. It's not yet a realistically practical attack vector, but should I be looking to move to SHA256/384/512 anytime soon? What might the security implications be of someone breaking the hash of a Strongswan VPN packet; to be able to fully read the packet, would they not have to break the AES128 ESP encryption as well?

Besides security, a reason I ask is because I have an Arch Linux router PC that has Strongswan site-to-site connections to a number of other standalone router/security appliance devices (Cisco ASA5505/5506, Ubiquiti EdgeRouter, etc.). Most of those devices support SHA-2 hashes, but enabling that on some of them causes throughput performance to nosedive, and I'd prefer not to have that happen...

SHA1 is being depraciated.
Microsoft announced its decision to deprecate the use of SHA1 from January 2017 and to replace it by SHA256. All certificates and intermediates signed in SHA1 won't be recognized anymore and will provoke security alerts on all the products of the brand.

Well, that's a reference to SHA1 being used in certificates. I'm talking about the use of SHA1 as the hashing algorithm for IPsec VPN packets. I'm using Strongswan as a VPN server daemon, but I suppose the question applies in a general sense for all VPNs.

SHA1 is Secure Hash Algorithm 1. I give you a fact, Microsoft certificates will give up SHA1.