word choice - Wishing someone good luck in continuing something without yourself without sounding hypocritical or sarcastic

How about something like ...

Mr. Smith,

Thank you for the opportunity to present our services to you. I appreciate your time and attention, and am grateful to have met you.

I hope we have an opportunity to work together in the future. May your project surpass all of your expectations. If I can serve you in any way, please, don't hesitate to contact me.

Sincerely

This approach wishes well, shows gratitude, while also putting you in mind for future opportunities.