I have seen a Phosco P567A (50w SON-T) replacing a SOX lantern here, and it took them about 2 years to remove the old SOX lantern and connect up the new P567A.
I have also seen a Philips SGS306 on a new pole that is stood next to a GEC Z8600 on a rusting steel post.
According to Google maps, the SGS306 was there in 2009 (the streetveiw only goes back to 2009, so it might have been installed even longer, maybe in 2007/8 ), but 8 years later the Z8600 and its pole have still not been removed, and its replacement is beginning to look old now as the GRP canopy of the SGS306 is getting weathered. I don't know if the SGS306 lights at night, or if the Z8600 is still going.

I see that it is snowing at your area now

This was actually taken a few weeks ago. It hasn't snowed since and I really miss it. In fact, the past few days have been around 60 F. If I wanted weather like this in the winter I would move to some other state.

Update: They have since added more concrete bases and have now added bronze poles with LED flyswatters on them. They are in an alternating patter, and while it's great to see a brand new installation, I just wish they were HPS or PSMH instead.