SQ B777s do not have 180 mins ETOPS clearance, only 120 mins. They have never had 180 mins ETOPS so to say so is misleading.
Midway has nothing to do with the vast majority of Vancouver ETOPS flights, it would though be relevant on ETOPS flights from Asia to destinations further south such as Honolulu. ETOPS suitable airports for Vancouver are much further North and consist of such places as Shemya, Adak, Cold Bay, Sapporo and a few in Russia whos names I could never hope to spell correctly. On very rare occasions when a southerly route is favourable Midway may come into the equation.
Etihad Girl, You're a great way to fly.