Disenchanting en masse is a terrible idea for the long term, as the process will never end: you'll have to keep dusting to maintain the Standard pace, sacrificing thousands of dust (particles?). Instead of shunning Wild, people should embrace the fact that they will eventually have a collection that makes Wild a viable alternative, and play in both modes. Fighting against the inevitable leads to a major loss on investment.
For me it is an easy decision. I disenchant everything on my two F2P accounts - I am quite sure I will never play Wild on them. On my pay to get all the cards account, I disenchant nothing.
You really shouldn't disenchant anything until you know what you want to use the dust for. And that doesn't happen until at least two weeks after the x-pac hits. Then that great deck you use your dust for might get hit with a balance patch. You can't predict when it might happen anymore. And you might someday want to play Wild.
You need to use your judgement. Many of the soon to be Wild cards are garbage anyway, and can probably be safely dusted. But you might want to hold onto some of the good ones, for the reasons stated above.
Honestly, if you don't really need to disenchant, don't do it. Wild is a fresh experience when you get bored of standard. There is way more variety in decks and is easier to find someone trying to do something wierd (funny). Or maybe just because you miss some cards...!
On top of that, if you stop playing hearthstone at any time, wild will always be there.
So no, there won't be any problem, but I wouldn't do it.
I've said this on tons of threads in many different ways so let me make it super simple.
Long-term: If you're planning on really sticking with this game (I mean like making it your primary video game) then keep your cards and build a collection. Use it for solo content, use it for tavern brawl, use it for your own enjoyment in wild if you have enough to make a decent deck. You don't have to have every card in wild to compete. My even oil rogue that I pulled off a player on this very site cost me only 400 dust outside of my collection, and got me to rank 12 in wild in one day from 25.
Short-term: You really have a flavor for this game and you don't know how long that will last. Dust it all. You started playing in 2017 and that means your collection is probably weak. Dust everything and focus on year of the raven and year of the dragon. Playing this game and having fun generally means playing standard ladder for a lot of players. You want to be able to play at least 3 decent meta styled decks whether or not you have all the cards to make said decks. The game can get repetitive, but its easier to grind with some semblance of variety. GLHF
You say you have almost all of Kobolds, Rasta and Boomsday? So, you only ask about the cards from Kobolds then.
Depending on how badly you need the dust or how much or little you care about Wild, maybe don't keep ALL of those cards. But Kobold is a very good set. Also, especially at lower ranks and in Casual, Wild is MUCH more fun from my experience.
I'd keep what I have, if I were you. Of course, I play the game for more than three years now, but I made that very same decision back in the day, when this whole Standard/Wild split started, just a few months after I picked up the game. By now, I play Wild regularly, and I am really, REALLY glad I bought the first wing of Naxxramas when I still had the chance. I even regret I didn't buy some more GvG packs before the rotation, because that set still has a good number of cards that are relevant to this day and that I'd like to have.
Unless there is a deck that you MUST play and need all the dust for, don't make this an "all or nothing" decision. Just continue playing the game, see what happens, see how it feels, and if you get to a point where you really don't give a damn about Wild anymore and want more resources for Standard, you can start disenchanting cards you don't need/want anymore. Simple as that.
I always dust. Don't let them fool you. You will have tons of dust on Day one and get to play with all the new cards you want to play with.
What can be better?
I'm never playing wild. I'm sure of that. I only kept some of the Hall of Fame goodies. You can always play new cards in Wild anyhow if for some reason you feel like it.
I like playing new cards. I'm never playing Wild !
Please listen to this guy and don't get baited by these people who love wild. There is ZERO incentive to playing wild for your growth in the game. No ranked rewards, little tournament representation, and all the growth in wild comes from new expansions. It is for enjoyment, nostalgia, and a change of pace. You are too new to the game to really benefit from any of those things except pure enjoyment. Pretty conditional on if you have the resources to build a deck you enjoy as well.
Making this decision now is very different from the first rotation imo.
Having a vast collection in wild makes it a fun play mode. I won't ever disenchant, but I have a strong collection featuring all expansions. For me, wild is very enjoyable.
If I just had some kobolds cards rotating (like OP states) I would probably dust that seeing only kobolds doesn't make me wanting to play wild. Year of the Mammoth is very strong. Not having too much of it would probably mean I would also dust year of the raven next rotation after going the dusting-path.
Maybe keep some iconic cards you love to play time to time?
So: disenchanting makes you probably disenchant in the future, which is a fine choice. You only get 1/4 of worth back, which is not great, but you already knew that.