BU slayed Bitcoin. Or Core did. Depending who you want to blame for the Scalepocalypse.
Well I think Bitcoin will come back up and still $2000+ eventually, but the long-term outlook for Bitcoin has become less certain.
Core offered their solution for bitcoin's problem, we can blame miners - not community for not accepting it (number of nodes speak for itself).
I see this differently. Bitcoin has the merit of being the first mover, but has also the oldest block chain tech. It contains several fundamental "flaws" or "features" if you want, which make that bitcoin cannot be what it is propagandized to be. It is/was a worthy proposal, and its current success shows how valuable these initial ideas were.
The oldest alt coins devs saw some of these problems almost immediately: litecoin saw the danger of ASICS and industrial mining (even though its Scrypt algorithm didn't survive either ASICS - but at least one understood this flaw in bitcoin). Peercoin realized the fundamental problems with PoW all together. It is amazing how well peercoin is designed as compared with bitcoin, btw even though it gave up on decentralized ultimate consensus. DASH realized the problem with transparent ledgers and the need for fungibility and privacy, but this wasn't really solved until cryptonote came out, originally with bytecoin, and which is right now done with Monero, who also solved the limited block size issue and the fee instability issue in a certain way.
Ethereum brought crypto to a whole other level, by allowing whole applications to run on top of it.
None of these coins are problem-free themselves, but they are all superior to bitcoin's system, individually. Some are damaged for ever by economic scams, but that doesn't mean that their technologies didn't all tackle serious flaws in bitcoin's system: PoW, asic mining, slow difficulty adaption, block reward halvings, limited blocks, transparent chain and traceable transaction history, ...
Bitcoin is what it is, with all of its design errors, but with its brand name of first mover. Bitcoin is designed to protect itself from change. This is something it does amazingly well, but this is also due to the uniqueness of its brand name, and the religious devotion that its users have towards this brand - somewhat like Apple customers. This is its most important value proposition: its brand name.
Core wanted to abuse an obvious design error, the block limit to 1 MB, to leverage it into a radical change: segwit. They didn't want to solve an easy issue (lifting the block limit or bringing it to a high value), in order to force bitcoin's community to accept a radical transformation of bitcoin. Bitcoin's immutability mechanism responded by introducing sufficient variants to that idea so that consensus over this radical change could not be found. As such, Core lost its centralized power over bitcoin by overplaying its hand.