This is a very broad question and I almost voted to close this as 'too broad'. The answer also depends quite much on what other assumptions we make about the business case.
So something like the following might be required as well:
1) Do you want to implement your business case with a blockchain at all? If yes, is Ethereum the right choice? Private or public Ethereum?
2) How will you write the contract, what testing framework will you use, how will you deploy the contract?
3) Should the contract be upgradable, should it use a proxy pattern, how are you planning to "update" it?
4) Does your contract have..well, bugs? Re-entrancy attack? Other security vulnerabilities?
5) Is usage of the contract feasible (gas wise)? How much do users need to pay to interact with your contract? Who are the end users and where do you get them?
And so on.