T-Mobile USA, whose plan to merge with MetroPCS Communications (PCS) could yet be disrupted by a last-minute takeover bid by Sprint Nextel (S), reported early Thursday that Q3 revenue fell 5.9% to $4.9 billion, as it continued losing high-spending customers. T-Mobile USA, owned by Germany's Deutsche Telekom, added 365,000 prepaid customers in Q3 but lost 492,000 postpaid subscribers. Postpaid subscribers sign service contracts and are billed