The way the laws are set up,
the 100W bulb is only the first to be “phased out”.
The 75’s, 60’s, and 40’s are to follow in subsequent years.
So, if you’re “stocking up” against the ban,
buy the bigger bulbs first, as they will be the first to be outlawed.
I’m assuming incandescents would have nearly unlimited storage life if kept in a dry location? I found some in the basement of my parents home that had to be from the 1950s, the paper sleeve was crumbling but the bulbs illuminated fine.