Re: Lock in
Firstly totally avoiding lock-in is an illusion. It would imply not using ANYTHING, so you're not locked-in. In reality it is a continuum and you evaluate the degree to which you're locked - from close to completely locked to almost free.
In the case of an array - you're locked to a large extent - you prepaid all the capacity you need + plus factoring some future growth; you need to buy the next box from them otherwise your creating siloes of storage, etc, etc.
In our case - we provide standard block device which is usually managed by cloud management software. If you decide that the solution is not your best choice - just click, copy your data and you're with another vendor. No complex migrations, different data formats and expensive professional services.
We have monthly recurring licensing plans, based on the capacity of your current system. In this case you haven't prepaid for the next 2-3 years. If next month you do not like it - you're free to switch. If you still want to commit and prepay for certain period - naturally you get good discounts for doing so.
The storage industry is being commoditized and is becoming more open. All vendors have to realize this and unless they provide great value and delight customers constantly - they'll go out of business. This is the new reality.