Seattle/Paris (Reuters) – The jumbo jet, for many years the workhorse of modern air travel, could be close to running out of runway. Last year, there were zero orders placed by commercial airlines for new Boeing 747s or Airbus A380s, reflecting a fundamental shift in the industry toward smaller, twin-engine planes. Sales forces at Airbus Group NV (AIR.PA) and Boeing Co (BA.N) are fighting for potential orders plane by plane as they seek to keep production going beyond the end of the decade, said other aviation market sources.