I have no experience of the DR1A DMU's and I don't know what the future holds in store for them so I can't really help you. I would guess that the Latvian Railways will want to replace them as soon as they can but I don't think any initial tendering processes have started whereas those for the new Skoda trains have been around for a few years and I believe that due to problems in how they were issued, the tenders had to be reissued. So I would think that they'll be around for some time yet. However, I have travelled on the class ER2 EMU's from Riga to Jurmala in 1995. These are very "clunky" Soviet era EMU's and well worth a trip if you have the opportunity. I once worked with a Russian engineer who played a leading role in the design and production of these trains which made the trip more interesting. Riga itself is a fascinating old Hanseatic city with a rich, but at times very painful, history. In fact. the whole country is fascinating and beautiful, again with a very painful history at times,
Digressing, Jurmala is also well worth a visit with a long curved beautiful sandy beach backed by pine forests, tastefully and sympathetically dotted with villas, sanatoria, hotels, restaurants and the like.
Meanwhile, Latvian Railways seem to have their hands full with teething problems with the new Skoda 16ev electric trains for Riga suburban services, such that Skoda are having to send extra staff to deal with them. Judging by reports, and I must emphasise that I am reading between the lines here, the problems may largely be down to software issues which may be connected with power collection from the overhead line (3.3kV). Below is link to Public Broadcasting of Latvia website reporting the problems.
For the third day in a row, train passengers have had to wait for hours as major delays were experienced, Latvian Television reported Thursday, January 4.
eng.lsm.lv