Hello Luc,
Currently, RadChartView for WinForms does not support flow chart and I am not able to engage with any time frame for such. A feature request for such is already available. Feel free to add your vote for it here: http://www.telerik.com/support/pits.aspx#/details/Issue=9101. The more votes a request gets the higher it gets in our priority list.
I hope that you find this information useful.
P.S. The other thread which you have opened regarding the same matter was deleted.