The issue in your statement is not about countable or uncountable nouns, but about verbs.
Whenever you have 'would' you always say 'change', never 'changes'
I would change, you would change, he would change, she would change, we would change, you (pl) would change, they would change.
Would life (singular) on this planet change?
Would my behavior change?
Would the rules of the game change?
'change' for all
You have a modal verb, which is followed by the base form of the verb.
Would, could, should, might, can are all modals that take the base form after them.
The base form is the same as in the infinitive 'to change' 'change'
I hope this helps