Undrave
Legend
Whatever it ends up being, we know that one of the ideas on the table is removing bonus actions. It's not that bonus actions are particularly bad in theory, most of them are fine, but they have caused the game designers no end of headache and have caused a lot of rules confusion among players (just have a look through Crawford's twitter feed to see the number of questions about bonus actions, and the mental gymnastics he goes through to explain what actions are allowed and in what order - and yes, sometimes the answers change with time).
They probably shouldn't have called it 'Bonus Action' and just called it a Minor Actor or Swift Action or whatever. It's way easier to explain 'you have a move, a standard and a minor action every turn' than 'some features LET you take a bonus action, but you can only take 1 bonus action per turn'. It feels needlessly wordy of a system. Otherwise I don't find it particularly difficult to grasp...
Similarly, we know from various rounds of Unearthed Arcana that one of the major hurdles they face in designing new classes/subclasses is pinning down the multiclass behavior. (There are also no end of questions online about multiclassing - particularly regarding spells and spell slots). A significant issue is that in 5E, there is explicitly no attempt to balance classes at any given level (rather, the stated goal is to balance them over the array of levels). Classes have totally different growth rates, even within the same class (for example, various Wizards subclasses: the Evocation wizard gets their best ability at level 2, the Transmutation wizard gets their worst ability at level 2).
It doesn't help that for some players (especially Wizard players

So, whether or not anyone likes multiclassing, we know that in its current iteration, multiclassing causes the game designers problems and we know that it is a source of confusion for players. In this light, and given the explicit goal of "appealing to the masses" it would not particularly surprise me if the game designers left it out of the next iteration. To me, feats seem like a decent alternative worth testing out because they are much simpler to tack on to a character than requiring detailed knowledge of multiple classes on top of special rules on how to combine them (in my experience, a lot of people don't fully understand their own class even on a single class build).
I could see traditional multi classing being relegated to an 'expert' book and the base game only having MC feats like they did in 4e. The 4e Paladin MC feat was great, letting anyone (in this case my Cleric) do a Divine Challenge once per encounter. Great way to off-tank!