QFF processes AA flight sectors based on the date provided by AA, so it should be safe for your membership year. Your only risk is somehow being delayed so that the last flight winds up being a day later (e.g. SYD-LAX diverts to NAN for medical emergency, which has happened surprisingly often in the past couple of years). But Silver is worth so little (primary benefit is the extra baggage allowance on QF, which I suppose can be worth hundreds for some).