“Gartner’s latest forecasts show that enterprises are realizing the most valuable assets they have are solid, long-term customer relationships. Trust really is the new currency, as my friend Michael Krigsman often says.” – Louis Columbus, Forbes. 
It seems that computer sciences are wiping the boundaries between everything, when human relations become the very energy of business – and in case of energy, you need what? Right, a constant supply of it anywhere, anytime, to power your world-reaching projects. In the next 10 years, there are going to be more mobile devices used than there are humans living (according to some cyber-prophets), which means, there are going to arise needs to reach to your clients on their move, while being on the move. And that, theoretically, points to decline of bulky on-premise systems in business.
Legacy CRM systems were designed in times of lower speeds of customer-manager interactions, aimed at two-week classes to get sales teams ready, but nowadays it’s all about quick launch and user-customizable mobile interfaces.
“It’s all about being quick enough to define new sales strategies, launch and measure them, making mid-strategy corrections if needed.” – Louis Columbus, Forbes. 
Forecasts and official reports on software world for past five years show growth of CRM as SaaS trend and its consistent implementation, which makes us hope for the same in near future.
But is it rapid growth or proportional? Is it essential in broad concept of cloud computing, or does something else, f. i., ERP, take first prize?
Without further ado, yes, CRM SaaS is the leading segment comparatively to ERP Saas, and one fast-growing.
For those who love dry data, let facts and figures speak.
In 2010 it was expected that with CRM world market of about $10.58 billion share of SaaS CRM would be about 32% (rising from $3.2 billion in 2010 to $3.8 billion in 2011); at the same time ERP SaaS offerings contributed approximately $1.5 billion to the SaaS market in 2010, and by year-end 2011, Gartner expects this to increase to $1.7 billion. 
In 2013 the market grew to more than $20 billion, with a prediction to have $36 billion up to 2017.
In 2014 we see stable growth of average 14% per year, which gives roughly expectation of having $33 billion market worth till said year 2017 and predictions of having more than 50% of this as SaaS CRM by 2015 .
In 2015 this number is corrected to 47% of $23.2 billion market .
We conclude that the growth is about 5-10% worse than the one hoped for, but still, Gartner anticipates “that SaaS deployments of CRM will reach a maximum 80% to 85% by 2025” .
Also, as experts foretell the whole SaaS market to reach more than $50 billion up to 2018, we could crudely calculate that CRM SaaS share would be about $20-22 billion out of these .