Usually March is lower than March, but at least with 3DS, many times March was flat or even better than February. March 2013 was way bigger than February, with a flat weekly sales avarange, March 2014 too was better than February, and March 2016 was slighly down, more like flat compared to February (176k VS 171k).
If Switch is able to reach 400k in february, it can do it even in March, but i personally believe that the 350-400K range for Switch in February/March looks more realistic.
About Far Cry, i think it'll sell over 500k, maybe 600k.
So you think Switch will go from a 50/60k a week in January to 90/100k a week in February. That seems extremely optimistic.
You don't know February trend then. In February console sales usually rise by 70/80%. Tax return month makes big boosts in sales, because people have money to spend. In some rare case the increase is also higher than x2.
It's not only Switch, every console are gonna have a big increase, all will easy surpass 300K.
Usually March is lower than March
*Lower than February