Revenue sharing is not a whole number. It is a percentage of league and individual team revenue:
http://www.nhl.com/ice/news.htm?id=643572
If league and team revenue rises, so does the amount of revenue sharing, thus offsetting a portion (at the very least) of the increases in payroll tied to HRR.
How exactly does it increase revenue? Revenue is money brought in. Just because expenses are reduced, does not necessarily mean that revenue increases.
I've already explained why it would only be a temporary fix: It does not address the real problem with the league, which is economic disparity, not payroll costs.
The league's growth is top-heavy. The top revenue generating clubs not only bring in the majority of money but are growing their revenues at a much faster pace than those at the bottom. The cap and floor are tied to that revenue growth. As the top clubs drive HRR upwards, they are also driving the cap and floor upwards. Bottom-tier clubs who cannot grow their revenues as fast are then left with higher salary costs which they cannot afford.
The only way to solve this problem is a redistribution of the wealth. A 50/50 split would cut costs in the short-term but would face the same escalating cap as has happened in the last seven years.