First of all, DashDrive has nothing to do with scaling. It's only going to store encrypted account information (user name and passwords and associated account numbers) That's it, no blockchain information.  However it *could* be used as a solution if no other solution is ever found to trim down the size of the blockchain.

Like afbitcoins said, as far as the blockchain is concerned, Dash nodes are incentiveised to run hardware with enough bandwidth, storage, CPU and RAM to serve up the blockchain quickly.

Eventually, the blockchain may indeed get too big and at that point, the best solutions people come up with will be used.  There is segwit, which is only a small fix, and removes a lot of information that might in fact be useful, so I'm not sure if it's the best way to go.  The other is block pruning and there may be others in the future.

Finally, the real way that Dash scales is the fact that we can process any amount of transactions per second while still being 100% decentralized and trustless.  That is through Masternode quorums.  Each MN quorum is limited to how many transactions can reach them IE: how fast the internet can deliver them) and how fast the individual computers can process them.  But what's neat is that these masternode quorums can lock transactions instantly then send the locked transactions to the miners for inclusion into the blockchain.  With many quorums working at the same time, the only limit is the number of Masternodes running.  So if we need more nodes, we simply reduce the collateral and force MNs with 1 node to operate 2 (by reducing the collateral to 500 coins)  This won't be an issue for a very long time though.  Currently, with blocks found every 2.5 minutes on average, we already have 4x the capacity of Bitcoin with a tiny fraction of the transaction numbers.

However, Dash has solutions to infinity, basically, or near as to it as you can get.  Scaling simply not an issue in Dash.