I'm bored, here's another crackpot theory. Ichigo is the same kind of quincy as Haschwald.
Ichigo's worthless classmates start the series unable to see or sense spirits. By the end of FKT arc, they could clearly see Aizen and Gin. The explanation given was that Ichigo's reiatsu had buffed their own. This is very similar to the effect that Haschwald had on Bazz-B during their childhood.
Ichigo had never shown any quincy powers prior to the war arc, and even then, only when in the presence of Yhwach. Prior to meeting Yhwach, Haschwald had no real quincy powers, and couldn't even manifest a spirit weapon.
This next bit is mostly a guess, but Yhwach identified Haschwald as "His other half" while the Yhwach Zangetsu claims to be a part of Ichigo. No other quincy has shown a Yhwach manifestation like Zangetsu.
Ichigo survived the Auswahlen before the start of the series, even though he isn't a pure quincy. If he had Haschwald-esque powers, this would make perfect sense.
And of course, Ichigo must always have all the powers of every possible thing ever, therefore he must be Haschwald.
Ichigo's worthless classmates start the series unable to see or sense spirits. By the end of FKT arc, they could clearly see Aizen and Gin. The explanation given was that Ichigo's reiatsu had buffed their own. This is very similar to the effect that Haschwald had on Bazz-B during their childhood.
Ichigo had never shown any quincy powers prior to the war arc, and even then, only when in the presence of Yhwach. Prior to meeting Yhwach, Haschwald had no real quincy powers, and couldn't even manifest a spirit weapon.
This next bit is mostly a guess, but Yhwach identified Haschwald as "His other half" while the Yhwach Zangetsu claims to be a part of Ichigo. No other quincy has shown a Yhwach manifestation like Zangetsu.
Ichigo survived the Auswahlen before the start of the series, even though he isn't a pure quincy. If he had Haschwald-esque powers, this would make perfect sense.
And of course, Ichigo must always have all the powers of every possible thing ever, therefore he must be Haschwald.