HANA isn't about lock-in
It's about getting a bigger share of the pie; what's the point going through an expensive sales cycle to get a customer and then have to hand over a large percentage of the profit to the company providing the DB software? SAP used to be pretty keen on MySQL, but its acquisition by Oracle probably cooled their ardour on open source a bit.
As far as lock-in goes, it's one thing to be locked into a software vendor, you can have escrow agreements in case they go out of business, but what do you do if the company has all your data? Any company looking at a cloud solution for a major part of it's infrastructure is basically saying "they are more likely to survive than we are"; which may be the case, but how can you know that? I'm sure some of these companies looked pretty solid too: