Just because Maldonado has suddenly popped up and qualified 2nd on the grid, inherited pole and won a race is no reason for Bruno to get worried or upset about his future within the Williams team.
He's been doing OK up until Spain so why would Frank look to push him out? up until Spain the following are the results of both drivers:
Australia neither driver scored points (unfortunate race for Maldonado)
Malaysia Sen 6th, Mal no points
China Sen 7th Mal 8th
Bahrain (even though I don't recognise this years race) neither driver scored
Spain Sen No points Mal 1st
So far Bruno has 14 points in 5 races while Maldonado has 29 , 25 coming from the win.
Hardly panic stations. So far Bruno is doing a decent enough job to warrant retaining his seat, he's only 4 points behind Kobayashi in the actual championship, the Sauber driver who is, so far, performing in the most consistent manner (Perez has only scored points in one race so far). In my Alternate Championship (- Bahrain) he's ahead of Di Resta in the Force India.
He's nicely placed to support the team as they go forward. There's a saying that "one swallow does not a summer make" - one victory, particularly in the current year, cannot overhype a team to the extent that they expect their drivers to be challenging for wins.
A non-story made much of by the F1 rumour mill. I'll withhold judgement until midway through the season, when all the driver's performances will come under scrutiny.