I'm in Canada and I noticed stores like Home hardware and home depot have removed their MV lamps and fixtures from their site...so the availability may not be long lived

As for 150W HPS, thats widely used here where I am, theres a blue burning HPS lamp in a cobra outside my house right now!
Its HPS but it lost its sodium over 2 years ago and looks like MV but still work just find and stable lol

My city was changing them to LED but has stopped because of poor budget so now EOL lamps in the cobras are just getting relamped as normal 

...and when the new LED fixtures fail within the next 3 months, they are really gonna be in the hole...

I thought that too but some LED fixtures have been there for 2 years and they seem fine .. unfortunately

..But they're horribly butt ugly and have poor light distribution and color. But there are other models in use in other neighbourhoods that have a nice even warm white colour to them.

A community 2 hours from me almost has no more HPS left but they seem to have retrofitted cool white induction lamps in the cobras. Other lights are LED fixtures shaped like cobra head fixtures and they either have a flat cover or the same drop lens and fixtures are black in colour