I just renewed a domain with Namecheap and, based on the price they're now charging, pretty sure the cost of this “free” whois privacy protection is now just built into the cost of their products. Not impressed. Edit: spelling
Jan 23rd 2018: $10.87 for .com and $0.99 for whoisguard ($11.86 total) 29th May 2018: $10.98 (+0.11) for .com and 0.18 ICANN'T fee ($11.16 total). So it's $0.71 cheaper without whoisguard. So that margin (increase in .com) probably covers the actual whoisguard cost, the $1 fee was pretty much pure profit.
For my same .com:
2017 New registration $10.69
2018 Renewal $12.98