I have a modest Dash holding from when Dash was a lot cheaper than it is now with the current price spike. I hold other coins too. What I'd like to ask is this -
Is Dash immune from blockchain bloat and, if it isn't, whether this will be an issue at some point in the future?
Dash has been founded in 2014, is three years old and currently has 2.6 GB blockchain size
Blockchain bloat is not and will not be a problem for Dash.
The Masternode network will continue to carry the full blockchain and getting rewarded for it, while the Dash Evolution update (end 2017) will enable Lightweight wallets SPV wallets for endusers merchants.
Here's my concern and you have highlighted it very well in your second paragraph. Dash will do doubt be used more as the number of payment providers increases. Mass adoption, if it happens, is bound to affect capacity available in each block. How can you say so definitely that blockchain bloat won't be a problem in the future?
By saying that lightweight wallets in an indirect way are a possible solution to blockchain bloat suggests that it will be a problem if Dash is widely adopted on an international scale. Lightweight wallets are off the blockchain and as such could be viewed as being prone to becoming centralized with all the perils associated with centralization.
By the way, I was stimulated to post after seeing the recent Bitcoin Core vs Bitcoin Unlimited debate which was mentioned in this thread the post before my original. Basically, I'm trying to work out which coins to concentrate on.
I can't really say that bloat will definitely never become a problem, but I don't find it likely. Even if it did, Dash's team has shown remarkable ability to solve unexpected problems. At one time, Evan discussed pruning a bit and seemed to think that it could be done. Since Dash's blockchain was (and is) so small, it wasn't something to spend dev resources on at the time.
Consider for a moment that mass adoption has swollen the size of Dash's blockchain to 5 TB:
Mass adoption will have led to much higher prices, meaning that masternode rewards will be much larger (in fiat terms). Right now a masternode makes about 8 DASH per month. Supposing that DASH was worth $1000 each, that masternode would earn $8,000 per month. However, in order to do that, the masternode must store and serve up the entire blockchain, which requires 5 TB of space. I did a quick perusal (I'm sure there are much cheaper options) and Vultr offers a 300 GB VPS instance for $160 per month, with additional storage available for $1/10 GB/month. To serve a 5 TB blockchain, a masternode owner would pay Vultr about $630 per month out of the $8,000 per month in masternode rewards.
Because there are 4500 masternodes, the blockchain is highly decentralized already. If the community felt that 4500 full nodes was too centralized, we could reduce the masternode collateral and thus create more masternodes. If we reduced the necessary collateral from 1,000 DASH to 250 DASH, we would (theoretically) end up with about 18,000 masternodes. Each one serves the full blockchain. Consumers could use SPV wallets without centralization fears, because incentivized masternodes hold the blockchain.
