One problem is that LOROL already operates DOO services on the ELL. It is not so very long ago that there was a thread on here ahead of the Clapham extension expressing concern over safety, etc because of certain areas it travels through. That did not wash with me then and it doesn't now.
The trains are busy at all times of day, they are well lit, they have clear CCTV and above all the fact that they are open carriages the whole length of the train makes for a pretty safe environment.
As a driver I might prefer to have a guard for other reasons. If things do go wrong it is indeed nice to have someone else to make announcements to passengers and keep them reassured whilst you remain focussed on safety critical issues, etc. It's always good to have someone else there (and indeed for them to assist in safety critical matters in the event of accident, evacuation, etc). These are rare events however and whether in this day and age a company can justify two different methods of operation across their network without valid reason I don't know. LOROL inherited guards on those sections of the network where they are employed rather than created them. I felt it was only a matter of time.
As I stated earlier, I feel desperately sorry for potential job losses but looking rationally I can see why this might be done. On the potentially negative side there are a couple of issues. Firstly, it would be the first major challenge for LOROL in terms of industrial relations and how that is managed (outside of the Travel Safe Officer dispute from which LOROL were one step removed by virtue of not employing Travel Safe Officers directly). Secondly, it would depend on how quietly it is done (partly dependent on the above) and whether there is significant passenger disquiet.
I might finally add that a lot will also ride on how redeployment and/or redundancy is handled. Thus far LOROL tend to have been fairly generous with regard to drivers who have been redeployed or 'moved on'. I would hope that this extends to guards.