Thanking multiple professors in an email thread I emailed one professor (with a few others CCed) to inform them that I will be following up with X commitment. Each professor on the thread replied (all) to state their well wishes and excitement. There has been no information or tasks requested from any of the members of this thread, so not any actual “need” to respond. 

Should I send some sort of thank you email, and if so, how should it be done?

The general consensus on SE for thanking professors in an email is to just do it when in doubt, however I do not think my question is a duplicate (or is necessarily answered by other questions I’ve seen) because it involves replying on a thread with multiple parties.
Don't overthink this. If this is still one E-Mail thread and every professor answered everyone else, write an e-mail to all saying "Thank you all for (whatever)". One more e-mail won't hurt, especially if it's clear that this e-mail is the last one and they can get the thing out of their mind.

I wish you the very best and good luck!!!