I think current gen will definitely get command blocks later this year when mods are officially supported and downloadable.
As for abuse of command blocks, that is easy. Leave that player's world. Simple enough
I'm not sure where your getting your information, but I'll bet a load of money that we will NOT be getting 'mods'. Mods are near impossible for the current code. The PC counterpart has a modding api that took years to develop and progress as that game went through version after version. The console version lacks this. Albeit its not entirely impossible, but certainly not for 'the average joe' to make a mod for the console version. I could list tons of reason for this but won't.
Now if your talking about DLC that's a different story, and again won't be something 'we' have much input on, that is unless you have an extremely high youtube following. 4J for the most part doesn't take much input from the community, if you haven't noticed. I could see 4J picking providing DLC based on the most popular MODS. Anyhow enough about that.
As for command blocks, I'm seeing them as a much more likely now that they have added book and quill which they first stated as not gonna happen. As to when, well that's anyone's guess.
Here's a statement that will hopefully start a new conversation about this topic.
how could you even abuse command blocks, say the host(antagonist) doesn't give anyone host privileges in creative and survival, survival you can't even open the block to input a vailed command but say there's a button next to it. owners mistake that's his fault it works the same way as it does it the computer version just take the button away and move the command block somewhere else. Now you say your in creative, you put down the block, you can't get into the block unless you have host privileges you would have to have /op or another command in the computer version for it to work. And say if they find you command block still owners fault they can just put it somewhere they can't get it creative or not. Say they do give the protagonist host privileges and he destroys the server with them. Worked the same way in computer, you just don't give people privileges if you don't trust them fully. So if your saying they shouldn't be added to Xbox why should they be added to pc in the first place.
theres one answer for that is they shouldn't be added till full servers host by players are added with plugins and in game chat, then you can add them for the safety of your world. It takes way too long for that to happen so don't expect it anytime soon may not even come around. Not because they are "abusive" that would make no sense. But if they added them to single player it would make sense to add them to multiplayer people would be happy if that answers your questions for not being able to add them in single player. So I would expect them anytime soon until they create player hosted servers and plugins.ect doesn't mean they have to add those things in it just make sense. That takes some time so don't get excited until those things happen.