Does not sound good at all.
Big picture, not going far this year (read: losing in the first round to a healthier opponent we could obviously beat if healthy) is not a big deal. The core is young apart from Horford and with luck they should be ready to do damage next year.
Nonetheless, it would be really disappointing if this season ends with Theis, Smart, and Kyrie all going out with long term injuries after the season began with Hayward lost for the year. Just a real bummer.
Still lots to feel good about this year, but it's hard to see them play so well when they had most of their guys and then have things fizzle out due to injuries.