Not to mention the dollars Google sunk into the Noto fonts. Also Chinese and Japanese fonts are expensive, and I'd wager that a lot of money is being spent in that space. Latin likely has the volume, but there's definitely money in non-Latin.
"TYPE" has a market cap of $824.36M, but even if the rest of the industry had a valuation in excess of $1.2B it would be hard to make the case. For that statement to be accurate the industry would need to be generating annual revenue in the billions. That's my five ¢.
I think you're in a difficult position. To add "next", "pro", "nova" or whatever to the font name you need to add some significant upgrades. If you don't feel as if you are doing that then the "2" seems reasonable, but I don't think there's much in the way of precedent or convention for this. If future updates are planned then maybe "Pro" with a beta tag might be appropriate, but betas are not usually charged for.
But ultimately if the metrics are changing I think a rename is appropriate so customers are able to opt in to content reflow.
Regarding name changes and Microsoft fonts. We try very hard to maintain the metrics of fonts when we update them. A bug has to be very serious or apply to an obscure glyph or font before we'd consider changing a character width. For fonts where the design/widths change we opt for a new name. Verdana Pro, Arial Nova being recent examples. We consider the version number important, but we don't expect an individual user to be aware of the version number.