It is very unlikely that an infant will self wean before 1 yr old. Some infants do - and in hindsight most moms agree that it was likely a "nursing strike" not true weaning. Weaning is gradual, one feed at a time. If you have a nursing strike on your hands when you get back, well, that can most likely be dealt with. And your determination to keep nursing or not will be the key to your success. And then again, he may not have any problems at all, especially if he is used to alternate care from your dh or a day care.
Since you asked, I would never seperate myself from a nursing baby for more than a few hours (especially if you are usually SAHM) unless it is a medical emergency. If my baby isn't used to me being away, it could cause him stress, anxiety, fear to be away from me, let alone not have his nursing for 3 days. Some times being a momma and putting my kids first, above my own needs, is tough. Giving up my "old life" wasn't easy. I'm the type that says, "if it isn't kid friendly, count me out" I'm a momma now. FWIW!
When my ds was 11 months, I had to be in the hospital for a day. My dh brought ds to me a couple times to feed. We just did what we had to do.