Tenants questioning lease expiration

[Jane S.]

The tenants' lease on their rental expires 12/31/23. I sent them a notice that the lease is expiring and they must vacate by 1 pm on 12/31. (I'm required to give them notice 90 days before the last day of the lease. )

They questioned why there is no mention of "signing  a new lease". So they wrote, that they are assuming that I "no longer want them to continue living there". 

How would you respond? The rental market has changed dramatically since they moved in 20 months ago. I would prefer to have the property vacant in case I decide to sell or change other terms.  Am I required to explain why I consider the end of the lease also the end of their tenancy? 

If I decide to rent to new tenants at a much higher rate, can they take me to court for refusing to renew them?

How can I respond without causing them to do damage because they are angry?

Most tenants don't argue about moving out. But they do leave premises in unsavory condition.

Thanks in advance for how you solved this or would solve this without tenants' bad feelings.