That's going to be a problem
Aside from the usual "Vas a tener problemas" etc.. What about "Habrás problemas" (heard today in a show) or "Te vendrá problemas" or what about with recaer sobre "to fall upon".
Jeezle, I think you heard "Habrá problemas" and "te vendrán problemas". Another common way is "van a surgir problemas".
There's always: Vas a meterse(te) en un lío.
You're going to wind up in a mess.
Eso va a causar problemas. / Eso será problematico. (are also possibilities)
That's going to be a problem But if you want to stick to that exact phrase, maybe something like 'Eso va a ser un problema'. Referring to some specific thing being the problem.