If the elections will be held in the region of Donbass, DNR and LNR will have the legitimate authority, able to appeal to Putin for military aid and support.
The first thing that comes to mind in connection with the deteriorating situation in the Eastern region of Ukraine, is that Putin is trying to keep Ukraine in a state of tension, exacerbate the destabilization, squeeze out the concessions demanded by the Kremlin: the constitutional changes concerning the "special status", the elections and the amnesty of DNR/LNR militants.
The second possible reason for the activation of the shelling is the necessity to maintain the internal order in pseudomilitary units of unrecognized republics. If they do not take up the fighting, there will be the problems of drug abuse, drunkenness and lawlessness, which will be followed by the righteous indignation "of the people" of Donbass. In such circumstances, the regime will lose the last bases of its legitimacy. Consequently, the separatists will not have anyone to rely on.
The third reason is probing of weak places in Ukraine's defense against a large-scale offensive. Many say that the attack will not happen, because Russia is afraid to get under the more severe sanctions.
Nevertheless, the Kremlin has a way to avoid this penalty. If the elections are held in Donbass, the unrecognized republics will have legitimate authority. Accordingly, it will have every reason to ask for the military aid from the Russian Federation. Little seems Putin worried by the fact, that this power is recognized by no one exept Russia. At least, it did not stop him at the signing of the military support contract with Ossetia, on the territory of which the Russian military base was established. And the West is unlikely to strengthen the sanctions against Russia, especially given the fact, that there is the on-going debate as for removing - or, at least, facilitating – them.
New military Russian units have appeared near the Ukrainian border, the fact speaking in favor of this version. In addition, the new units are reported to be spotted on the territory of Donbass. We can assume that they are being trained. However, to be trained just for the sake of training is too expensive.
Another thing, if it is a preparation for something specific, in particular, for military advance. For Ukraine, it will be the hardest option. The only good news is that both the President and the General Staff of Ukraine are beginning to talk about a possible attack.
According to Putin’s plan, the probability of military advance, should disquiet the entire political elite of Ukraine and force it to make concessions
It is not known whether this will really happen, but one needs to be prepared for every twist and turn. Putin, of course, will make the maximum use of political leverages, forcing both Ukraine and the West, to act in his favour. If they do not work, the probability of attack will increase significantly. Moreover, the very likelihood of such a scenario, according to the Russian President, should lead to intimidation of the entire Ukrainian political elite and forcing it to make concessions.
Until recently, everyone thought that there could not be a war between the former Soviet States. It was a mistake. Here it is. So every scenario is possible.