Will Fenix 7 Solar (Non-Pro) get Multiband in the next quarterly update?

It's simply not possible. They don't contain the hardware so it can't be added by firmware.

No, as Senecio said, this is a hardware issue, not software - the non-pro models have a completely different chipset, and you can’t just upgrade that.. 

Not completely different, but a different variant of the same chipset nevertheless. Between the two chipsets everything is the same except multi-band availability. 

It's not a different chipset, sorry. It's the same chipset that works exactly with same performance on both devices with all systems and gps only. Also the same antenna design.

If fenix 7 base and solar model doesn't have multiband gps, it is a marketing decision made by Garmin. Completely fair decision. But they can enable if they want.

Honestly, don't think they will enable it. But I was also convinced that coros will never allow the navigation on the Pace 2. I was wrong there. Let's hope I am also wrong here.

Someone posted a teardown of the base Fenix 7 on this forum. You can probably find it. The base Fenix 7 has Airoha AG3335MN while the sapphire version has AG3335M.

That extra N at the end makes the difference. That was a variant created specifically for IRNSS (Indian regional navigation system) it seems. Why did Garmin decide to use it in the base Fenix 7 is another question - probably due to chip shortage at the time. 

Thanks for your clarification. I was so wrong then.

Which Fenix 7 are you referring too? I have the 7x solar sapphire edition and it received multi band gps in a software update some months ago. 

The 7x solar sapphire edition had multiband since release. The only new thing is the automatic option that selects multiband only when the watch thinks, it is needed....

All Fenix 7 Sapphire editions have multi band.